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IC 


9025 



Bureau of Mines Information Circular/1985 



Tungsten Availability— Market 
Economy Countries 

A Minerals Availability Program Appraisal 



By T. F. Anstett, D. I. Bleiwas, 
and R. J. Hurdelbrink 




UNITED STATES DEPARTMENT OF THE INTERIOR 



CD 
C 
33 

m 
> 

c 

9c 



751 

*f/NES 75TH A^ 



Information Circular 9025 

A 



t^JjU M*&< , fUnuM *£ Hm^ 



Tungsten Availability— Market 
Economy Countries 

A Minerals Availability Program Appraisal 



By T. F. Anstett, D. I. Bleiwas, 
and R. J. Hurdelbrink 







UNITED STATES DEPARTMENT OF THE INTERIOR 

Donald Paul Hodel, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



As the Nation's principal conservation agency, the Department of the Interior 
has responsibility for most of our nationally owned public lands and natural 
resources. This includes fostering the wisest use of our land and water re- 
sources, protecting our fish and wildlife, preserving the environmental and 
cultural values of our national parks and historical places, and providing for 
the enjoyment of life through outdoor recreation. The Department assesses 
our energy and mineral resources and works to assure that their development is 
in the best interests of all our people. The Department also has a major re- 
sponsibility for American Indian reservation communities and for people who 
live in Island Territories under U.S. administration. 



^■{vlE^ 




^ -0 



*V 



4< 



Library of Congress Cataloging in Publication Data: 



Anstett, T 4 F. (Terrance F.) 

Tungsten availability —market economy countries. 

(Information circular ; 9025) 

Bibliography: 51; 

Supt. of Docs, no.: I 28.27:9025. 

1. Tungsten industry. I. Bleiwas, Donald I. II. Hurdelbrink, 
Ronald J. III. Title. IV. Series: Information circular (United States. 
Bureau of Mines) ; 9025. 



TN295.U4 [HD9539.T8] 622s [338 6 2'74649] 84-600367 



For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 






«• PREFACE 

• ' The Bureau of Mines is assessing the worldwide availability of nonfuel critical 

minerals. The Bureau identifies, collects, compiles, and evaluates information on active, 
developed, and explored mines and deposits and mineral processing plants worldwide. 
Objectives are to classify domestic and foreign resources, to identify by cost evaluation 
resources that are reserves, and to prepare analyses of mineral availability. 

This report is part o\' a continuing series of reports that analyze the availability 
of minerals from domestic and foreign sources. Questions about these reports should 
ssed to Chief. Di\ ision of Minerals Availability. Bureau of Mines, 2401 E Street, 
XV ..on. DC 20241. 



in 



M 



CONTENTS 



Page 

Preface iii 

Abstract 1 

Introduction 2 

Tungsten products and uses 2 

Tungsten pricing 3 

Tungsten concentrate price indicators 3 

Price indicators for tungsten products 4 

World tungsten production, consumption, and 

trade 5 

Production and consumption 5 

World trade 5 

U.S. production, consumption, and imports 6 

Geology and resources 7 

Evaluation methodology 7 

Geology of tungsten deposits 9 

Market economy countries 10 

Australia 10 

Austria 12 

Bolivia 13 

Brazil 15 

Burma 15 

Canada 15 

France 16 

Mexico 17 

Namibia 17 

Peru 18 

Portugal 18 

Republic of Korea 18 

Spain 18 

Sweden 19 

Thailand 19 

Turkey 19 

Uganda 20 

United Kingdom 20 

United States 20 

Centrally planned economy countries 22 

China' 22 

U.S.S.R 23 

Mining and postmine processing technology 24 

Mining methods 24 

Surface 24 

Underground 26 

Solution 26 

Beneficiation of tungsten ores 26 



Page 

Post mill processing 28 

Ammonium paratungstate (APT) 28 

Artificial scheelite 29 

Scheelite concentrate 30 

Ferrotungsten 30 

Operating and capital costs 31 

Operating costs 31 

Surface and underground 31 

Regional overview 32 

Producers 32 

Nonproducers 33 

Producers versus nonproducers 33 

Postmill transportation and processing 33 

Transportation 34 

Processing costs 34 

Ammonium paratungstate (APT) 34 

Ferrotungsten 35 

Artificial scheelite 35 

Scheelite concentrate 35 

Capital costs 36 

Mine and mill capital ' 36 

Postmill capital 36 

Ammonium paratungstate (APT) 37 

Ferrotungsten 37 

Artificial scheelite 37 

Tungsten availability— market economy countries . 37 

Evaluation methodology 38 

Tungsten availability 40 

Scheelite concentrate 40 

Total availability 41 

Annual availability 42 

Ammonium paratungstate (APT) 42 

Total availability 42 

Annual availability 44 

Ferrotungsten 45 

Total availability 46 

Annual availability 46 

Tungsten availability— all product forms 

combined 46 

Total availability 46 

Annual availability 47 

Conclusions 49 

References 51 



ILLUSTRATIONS 



1. Simplified tungsten flow diagram 2 

2. World annual tungsten concentrate production and consumption, 1973-82 5 

3. MEC and CPEC production and consumption of tungsten concentrate, 1973-82 6 

4. World tungsten trade pattern, early 1980's 6 

5. U.S. annual tungsten production, consumption, and import data, 1973-82 7 

6. Sources of tungsten ore and concentrate imports to the United States, 1973-82 7 

7. Classification of mineral resources 9 

8. Demonstrated contained WO, resources for MEC deposits evaluated 11 

9. Location map, Australian deposits 11 

10. Location map, European deposits 13 

11. Location map. South American deposits 13 

12. Location map. southeast Asian deposits 15 

13. Location map, Canadian deposits 16 

14. Location map. Mexican and U.S. deposits 17 



VI 



CONTENTS— Continued 

Page 

15. Location map, southern African deposits 17 

16. Total recoverable resource by status and mine type 25 

17. Total ore capacity by status and mine type . . . : 25 

18. Flowsheet, Mount Carbine operation 27 

19. Flowsheet, Sangdong concentration process 28 

20. Flowsheet, ammonium paratungstate production process 29 

21. Flowsheet, artificial scheelite production process 29 

22. Flowsheet, ferrotungsten production process 30 

23. Operating costs, surface versus underground 31 

24. Operating costs, regional basis 32 

25. Estimated mine capital for selected undeveloped properties 36 

26. Minerals Availability Program evaluation procedure 38 

27. Total production costs 39 

28. Total W0 3 potentially available from scheelite producers at 15- and 0-pct DCFROR's 41 

29. Annual W0 3 potentially available from scheelite producers at various average total costs 42 

30. W0 3 potentially available as ammonium paratungstate 43 

31. Total W0 3 potentially available from ammonium paratungstate producers at 15- and 0-pct DCFROR's . . 44 

32. Total W0 3 potentially available from ammonium paratungstate nonproducers at 15- and 0-pct 

DCFROR's 44 

33. Annual W0 3 potentially available from ammonium paratungstate producers at various average total 

costs 45 

34. Annual W0 3 potentially available from ammonium paratungstate nonproducers at various average total 

costs 45 

35. Total W potentially available from ferrotungsten deposits at 15- and 0-pct DCFROR's 46 

36. Annual MEC W0 3 availability and projected demand, 1983-95 48 

TABLES 

1. Tungsten prices 4 

2. MEC tungsten deposit information 8 

3. MEC tungsten demonstrated resources used for analysis, January 1983 10 

4. CPEC in situ resources, January 1983 23 

5. Mine ore capacity, mining and beneficiation methods, product, and status 24 

6. Chemical composition of APT 29 

7. Chemical composition of natural and artificial scheelite 30 

8. Chemical composition of ferrotungsten 30 

9. Commodity prices used in study 32 

10. Actual or assumed destinations for tungsten concentrate 34 

11. Port handling and transportation costs for selected major tungsten concentrate trade routes 35 

12. Estimated operating costs for a 2-million lb/yr APT plant 35 

13. Estimated operating costs for a 1,000-t/yr ferrotungsten plant 35 

14. Estimated operating costs for a 1-million-lb/yr (W0 3 ) artificial scheelite plant 35 

15. Estimated capital costs for a 2-million-lb/yr (W0 3 ) APT plant 37 

16. Estimated capital costs for a 1,000-t/yr ferrotungsten plant 37 

17. Estimated capital costs for a 1-million-lb/yr artificial scheelite plant 37 

18. U.S. market price for tungsten concentrates 41 

19. U.S. market price for APT 43 

20. U.S. market price for ferrotungsten 46 

LIST OF UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 



°c 


degree Celsius 


m 2 


square meter 


cm 


centimeter 


mm 


millimeter 


ha 


hectare 


pet 


percent 


kg 


kilogram 


ppm 


parts per million 


km 


kilometer 


t 


metric ton 


km 2 


square kilometer 


t/d 


metric ton per day 


kW-h 


kilowatt hour 


tr oz 


troy ounce 


lb 


pound 


t/yr 


metric ton per year 


lb/yr 


pound per year 


wt pet 


weight percent 


m 


meter 


yr 


year 



TUNGSTEN AVAILABILITY— MARKET ECONOMY COUNTRIES 
A Minerals Availability Program Appraisal 

By T.F. Anstett, 1 D.I. Bleiwas, 1 and R.J. Hurdelbrink 2 



ABSTRACT 



The Bureau of Mines estimated the potential availability of tungsten from 57 mines 
and deposits in 19 market economy countries. The tungsten resources of China and the 
U.S.S.R. were also estimated. This resulted from an evaluation of tonnage-cost rela- 
tionships indicating the quantity of tungsten available as ammonium paratungstate 
| APT), artificial and natural scheelite, and ferrotungsten at various average total costs 
of production including 0- and 15-pct rates of return on invested capital.. 

The evaluated deposits contain 1.2 million metric tons (t) of recoverable W0 3 , of 
which approximately 52,000 t of APT can be produced at the January 1983 market price 
of $5.37 lb. 89,000 t of natural and artificial scheelite at a market price of $3.63/lb, and 
1,700 t of feiTotungsten at $5.61/lb of tungsten. An annual availability analysis indicates 
that by the early 1990's new deposit discoveries, development of known prospects, or 
expansions of producing mines will be necessary to meet projected tungsten demand. 



'Geol> _ 

industry economist 
Minerals Availability Field Office. Bureau of Mines. Denver. CO. 



INTRODUCTION 



Tungsten is a metal critical to modern industry, chiefly 
owing to the ability of the metal to retain great hardness 
at high temperatures. For this reason it is an important 
constituent of high-speed drilling, cutting, and milling tools. 

This Bureau of Mines study addresses the potential 
availability of tungsten as ammonium paratungstate (APT), 
natural and artificial scheelite, and ferrotungsten from 57 
mines and deposits in 19 market economy countries 
(MEC's). The study evaluates the geologic, engineering, and 



economic factors affecting the potential availability from 
the 57 MEC mines and deposits, and addresses the resources 
of 38 tungsten deposits in two centrally planned economy 
countries (CPEC's), China and the U.S.S.R. 

The major production cost factors affecting the 
availability of tungsten from each deposit are part of this 
evaluation, including mining and beneficiation costs; pro- 
cessing costs for APT, artificial and natural scheelite, and 
ferrotungsten; and costs of transportation. 



TUNGSTEN PRODUCTS AND USES 



Tungsten was first isolated from its ore minerals in the 
1780's, although the name was first used in 1755. The first 
significant industrial application was in tungsten- 
manganese steel in the mid-19th century. Worldwide, most 
tungsten is marketed in four major intermediate forms: con- 
centrate, APT (the major intermediate product in the United 
States), ferrotungsten, and artificial scheelite. Virtually all 
other tungsten products are derived from these forms and 
from scrap, as illustrated in figure 1. 



Concentrate is either converted into intermediate 
products such as APT, or, in the case of some scheelite con- 
centrates, used as a direct additive to molten steel. In order 
to be an acceptable additive, the concentrate must meet 
strict assay requirements. Some concentrate is converted 
directly into tungsten carbide powder. 

The addition of natural or artificial scheelite to steel 
imparts properties of greater hardness, wear resistance, and 
high heat resistance. It is an important constituent of steel 




Tungsten 
ore 



Tungsten 
concentrate 




Artificial 
scheelite 



Scrap 



Ferro- 
tungsten 





Scrap 



Superalloys 



Tungsten 

metal 

powder 



Tungsten 
carbide 
(powder, 
cast, 

crystalline) 




Carbide 
tools 

and wear- 
resisting 
materials 



--J 



Tungsten 

mill 
products 



Tungsten 
chemicals 



Chemicals 

and 
ceramics 



Figure 1 .—Simplified tungsten flow diagram. 



for tools, drill bits, and other similar applications. In some 
cases, artificial scheelite can be used as a direct additive 
to steel baths. 

Nearly all APT is reduced to tungsten metal powder, 
most of which is used to produce tungsten carbide powder. 
Most of the remaining metal powder is used for a large 
variety of different products. Tungsten carbide accounts for 
more than 60 pet of total tungsten consumption in the 
United States. The tungsten carbide is cemented, usually 
with cobalt, to form various cutting and wear-resistant 



cemented carbide products. Most tungsten carbide is used 
for metalworking machinery and by the mining and oil in- 
dustries for which tungsten carbide's high melting point, 
high compressive strength, hardness, and resistance to ox- 
idation are necessary, particularly for working metals at 
high speeds. 

The major use of tungsten metal powder is in wire, rod, 
and sheet form as filaments in electric lamps and other 
purposes, but it is also used for electrical contacts, welding 
rods and electrodes, and armor-piercing ammunition. 



TUNGSTEN PRICING 



In contrast to what happens in many basic commodity 
markets, there are no terminal market quotations for 
tungsten ore. Almost all transactions involve a milled or 
processed form of tungsten with sales negotiated between 
producers and consumers or merchants and users. Terms 
of purchase can vary with every sale. There are prices 
reported on a regular or semiregular basis for tungsten con- 
centrate, tungsten metal powder, tungsten carbide powder, 
and feiTotungsten. and additional information about actual 
prices paid can be gleaned from national trade statistics. 
However, none of these prices are normally used for pric- 
ing purposes 'except the concentrate price! and could be bet- 
ter described as price indicators. 

This near lack of a common pricing basis reflects the 
wide variation in the chemical makeup of tungsten 
materials, as well as the diversity of requirements for 
different users with respect to impurities and tungsten con- 
tent for each of the possible tungsten products. Those con- 
tracts that do use a published concentrate price as a basis 
adjust the actual price paid to reflect such things as con- 
taminants, tungsten content, tariff barriers, and the par- 
ticular needs of the purchaser. 



TUNGSTEN CONCENTRATE PRICE INDICATORS 

There are three regularly published price indicators for 
tungsten concentrates, the Metal Bulletin, the International 
Tungsten Indicator <ITIi. and Metals Week. The Metal 
Bulletin of London publishes a price twice weekly that 
reflects reports from producers, consumers, and merchants 
of prices at which they actually concluded transactions in 
the half week immediately prior to publication. The Metal 
Bulletin quotation is published as a range, with the dif- 
ference between high and low generally being a small 
percentage of the average reported sales price. The Metal 
Bulletin coverage is for Western Europe and includes only 
relatively clean, standard grade 'i.e., greater than 65 pet 
framite that has no special payments or currency 
terms attached to it. The Metal Bulletin's quotation is based 
on the sale of only about 10 pet of estimated world produc- 
tion, but it must be noted that a large proportion of world 
tungsten production is never sold under conditions that 
would allow its inclusion in any of the price indicators; 
nevertheless, most sales are related to published price in- 
dicators The Metal Bulletin's quotation is the most widely 
used pricing basis, accounting for over 50 pet of deliveries 
in 1981 (l). 1 



.- numbers in parentheses refer to items in the list of references at 
the end of this report 



The other widely used reference price is the ITI, pub- 
lished twice monthly, which reflects deliveries made 2 to 
4 weeks earlier. All concentrates (wolframite, natural 
scheelite, and artificial scheelite) containing between 60 and 
79 pet W0 3 are taken into account, and both spot sales and 
sales under long-term contracts are included in the forma- 
tion of the ITI. The average grade of the tungsten concen- 
trates sold varies with each biweekly report, making it more 
difficult to use consistently as a basis for pricing. Sales of 
about 25 pet of world tungsten production are reported to 
the ITI, and approximately 25 pet of tungsten deliveries in 
1981 were priced using the ITI as a reference price (7). 

The only other regularly published indicator of the 
tungsten concentrate price is a Metals Week quotation for 
spot purchases by U.S. consumers of tungsten concentrates 
containing more than 65 pet W0 3 . Like the ITI, it includes 
spot deals for scheelite. The Metals Week coverage is less 
extensive than for either of the other two indicators. The 
small volume of transactions reported makes the Metals 
Week quotation susceptible to manipulation and it is, 
therefore, rarely used for pricing purposes. 

There has been some discussion recently about 
establishing a price indicator for low-grade concentrates, 
the trade of which has grown in importance in recent years. 
To expand the coverage of the current indicators to include 
low-grade concentrates might be unwise, as it would pro- 
vide only an average price for a nonexistent, middle-grade 
concentrate and would not suit the reference price needs 
in either the standard- or low-grade tungsten concentrate 
markets. The Metal Bulletin feels there is currently not a 
large enough set of market transactions to justify publishing 
a separate quotation for low-grade concentrate transactions, 
but leaves open the possibility of establishing such an in- 
dicator in the future (1). 

Table 1 shows historical values for each of the regularly 
published concentrate price series, as well as a U.S. market 
price published annually in the Bureau's Mineral Commod- 
ity Summaries and a constant dollar series based on this 
U.S. price. The constant (January 1981) dollar price series 
was constructed by deflating the current dollar series with 
the price index for Metals and Metal Products published 
by the U.S. Department of Labor 12). Values for the Metals 
and Metal Products index (value in 1981 equals 100) are 
also shown in table 1. The January 1981 dollar values for 
the concentrate price were used in the "Tungsten Availabil- 
ity" (scheelite concentrate) section as a reference price 
against which the results of the cost analyses were 
interpreted. 

As is evident in table 1, the U.S. market price series 
matches very well with the annual averages of all the other 



Table 1. — Tungsten prices, U.S. dollars 



Product form 1973 1974 1975 1976 

CONCENTRATE* 
Current dollars: 

U.S. market 3 $2.21 

Metal Bulletin 2.01 

Metals Week NAp 

ITI NAp 

January 1981 dollars: U.S. market 4 5.00 

APT* 
Current dollars: 

U.S. market 5 3.00 

Union Carbide 2.53 

January 1981 dollars: U.S. market 6 6.80 

FERROTUNGSTEN 7 
Current dollars: 

U.S. market 5 3.27 

Metal Bulletin 4.60 

January 1981 dollars: U.S. market 6 7.40 

MMP index 44.2 



1977 



1978 



1979 



1980 



1981 



1982 



1983' 



$4.20 


$4.38 


$5.38 


$7.95 


$6.41 


$6.37 


$6.55 


$6.51 


$4.90 


$3.63 


4.00 


4.16 


5.20 


7.74 


6.52 


6.30 


6.55 


6.51 


4.81 


3.62 


NAp 


NAp 


NAp 


7.39 


6.40 


6.37 


6.50 


6.46 


4.87 


3.73 


NAp 


NAp 


NAp 


NAp 


NAp 


6.31 


6.47 


6.49 


5.13 


3.79 


7.34 


7.09 


8.25 


11.42 


8.48 


7.38 


6.87 


6.51 


4.88 


3.63 


5.28 


5.54 


6.63 


9.38 


7.87 


8.00 


8.33 


8.36 


6.69 


5.37 


4.40 


5.50 


5.91 


8.73 


8.10 


8.08 


8.56 


8.62 


NAp 


NAp 


9.23 


8.96 


10.18 


13.48 


10.41 


9.27 


8.74 


8.36 


6.66 


5.37 


5.98 


6.25 


7.58 


10.96 


9.02 


9.06 


9.38 


9.37 


7.28 


5.61 


NAp 


NAp 


7.32 


10.50 


9.77 


9.66 


9.37 


9.05 


NAp 


NAp 


10.45 


10.12 


11.63 


15.75 


11.93 


10.52 


9.84 


9.37 


7.24 


5.61 



57.2 



61.8 



65.2 



69.6 



75.6 



86.3 



95.3 



100.0 



100.5 



100.0 



APT Ammonium paratungstate. 
ITI International Tungsten Indicator. 
MMP Metals and Metal Products. 

NAp Not applicable. For concentrate, Metals Week price series created in 1977, ITI series created in 1979: for APT and ferrotungsten, price series withdrawn 
in certain years. 
'Price as of January 1983. 
2 Per pound of W0 3 . 

3 From Bureau of Mines Mineral Commodity summaries, various issues. 
"Calculated from the U.S. market price using the MMP price index. 

5 Calculated using the U.S. market price for concentrate and formulas given in the "Price Indicators for Tungsten Products" section of this report. 
Calculated using the current dollar U.S. market price and the MMP index. 
7 Per pound of tungsten. 



regularly published prices for concentrate. This U.S. market 
price for concentrate is also used as the basis for calculating 
a number of other annual average price series (i.e., APT 
and ferrotungsten) because no other regularly published 
series for the U.S. market exists for these products. 



PRICE INDICATORS FOR TUNGSTEN PRODUCTS 

Marketing and pricing practices for processed tungsten 
products are more diversified than for concentrates. Prod- 
uct differentiation and tariff barriers contribute to creating 
a situation in which prices for what is nearly the same prod- 
uct can vary by large amounts from market to market. 
Representative reference prices such as the concentrate in- 
dicators just discussed are more or less nonexistent. Prices 
of processed products published in trade journals are studied 
as indicators of the market situation, but are not used as 
the basis for prices in individual contracts (1). 

There currently is only one published price for APT. 
Union Carbide Corp. had published a producer price for APT 
until October 1981, when falling demand led it to suspend 
the price as a means of dealing with increased competition. 

Contract prices for APT are sometimes set on the basis 
of the Metal Bulletin's quotation for concentrates adjusted 
for conversion losses. A typical price formula might be as 
follows (3): 

APT price in U.S. dollars per metric ton unit W0 3 = 

Metal Bulletin/0.96 + conversion charge. 
However, many trades are made with prices negotiated 
between buyer and seller without direct reference to any 
published quotation for concentrates. 

Table 1 shows the published Union Carbide list price 
for APT and a price series (U.S. market price) that is 
calculated from the U.S. market price for concentrate using 
the formula shown. The conversion charge used in the for- 



mula was $35 per metric ton unit in 1982 and the Metals 
and Metal Products index was used to derive a current 
dollar converison charge for the other years. The two price 
series correlate relatively well over time, with values dif- 
fering by only a few percent in most recent years. Both 
series catch the peak price level in 1977. A January 1981 
dollar price was constructed from the U.S. market price us- 
ing the Metals and Metal Products index and it was used 
in the "Tungsten Availability" (ammonium paratungstate) 
section of this report to aid in the interpretation of the 
evaluation results. 

Ferrotungsten prices for the United Kingdom and for 
Western Europe are published by the Metal Bulletin. The 
quotations change relatively infrequently (approximately 
once a month for the United Kingdom indicator and once 
every 3 months for the Western Europe indicator) and the 
quote is useful for reference purposes only. Prices in long- 
term contracts are normally based on the Metal Bulletin 
concentrate quotation according to a fixed formula. A 
typical pricing formula might be as follows: 

Ferrotungsten price in U.S. dollars per kilogram unit 

W = 0.13 X concentrate price + conversion charge. 

The 0.13 factor reflects a conversion of quantities from 
metric ton units W0 3 in concentrates to 1 kg of W in fer- 
rotungsten, and includes compensation for conversion losses 
(3). 

A Union Carbide producer price for ferrotungsten was 
discontinued in October 1981, at the same time as the APT 
producer price was discontinued, and has not yet been 
reestablished. The Union Carbide ferrotungsten quotation 
changed every third or fourth month and showed only a 
weak correlation with the Metal Bulletin ferrotungsten 
price. This is to be expected since producer prices generally 
do not adjust quickly to changing market conditions, and 
the end-use markets for Union Carbide ferrotungsten are 
different from the end uses for ferrotungsten in Europe (only 



a very small amount of the former is used in steel). Also 
contributing to the weakness of the relationship between 
the indicators was a difference in the product traded, with 
Union Carbide's ferrotungsten having higher tungsten con- 
tent and purity. 

Table 1 shows the Metal Bulletin quotation for the 
United Kingdom, and a price series (U.S. market price* 
calculated from the concentrate price according to the for- 
mula shown. The conversion charge used in the fer- 
rotungsten formula was $2 kg of W in 1982. and the Metals 



and Metal Products index was used to approximate a cur- 
rent dollar conversion charge for the other years. A January 
1981 dollar price series is also shown in table 1. It was con- 
structed in a similar manner to the concentrate and APT 
constant dollar series; that is. the U.S. market price series 
was deflated with the Metals and Metal Products index. 
This constant dollar price was used in the "Tungsten 
Availability" (ferrotungsten) section of this report to aid in 
interpretation of the results of the evaluations. 



WORLD TUNGSTEN PRODUCTION, CONSUMPTION, AND TRADE 



The following figures and discussion provide a general 
overview of world tungsten production, consumption, and 
trade. More detailed information and data are available 
from several Bureau of Mines publications, most notably 
the annual Minerals Yearbook. 



PRODUCTION AND CONSUMPTION 

Figures 2 and 3 illustrate annual MEC and CPEC 
tungsten production and consumption values for 1973 
through 1982. Prior to 1980. MEC's accounted for slightly 
more than half of world production; however, after that 
year. CPEC's accounted for slightly more than half (left, 
fig. 2 1. Throughout the 1973 to 1982 period, MEC's and 
CPEC's produced approximately equal amounts of tungsten. 
The situation is different in terms of world consumption. 
Estimated CPEC consumption was far below that for MEC's 
in the early part of the period, increased dramatically 
relative to the MEC's between 1973 and 1980, and has ex- 
ceeded MEC consumption since 1980. 

Figure 3 illustrates that MEC production and consump- 
tion have been more or less in balance since 1975, before 
which consumption outpaced production by a sizable 



amount (15 pet greater in 1973, 23 pet in 1974). CPEC pro- 
duction, on the other hand, significantly led consumption 
until the late 1970's. Consumption averaged only 78 pet of 
production during the 1973 to 1977 period. By 1978, CPEC 
consumption had increased to more or less come in balance 
with production. While it is not possible to extrapolate 
production-consumption trends with a high degree of ac- 
curacy, the analyses of tungsten availability contained in 
this report indicate that, at least in the short term, MEC's 
are capable of maintaining or even increasing current pro- 
duction levels. However, given China's enormous resources 
(discussed in the "Geology and Resources" section of this 
report) and resultant production potential, the possibility 
exists for China to control and disrupt the world market 
price structure. In the longer term, it appears that China 
will play an increasingly important role as a supplier of 
tungsten to the MEC's. 



WORLD TRADE 

The general world tungsten trade pattern as it currently 
exists is illustrated in figure 4. China is the world's largest 
exporter of tungsten. It consumed, on average, less than 7 






«- 40 
O 



KEY 
t .i Market economy coun-nes 
^j Centrally planned economy 
coun'nes 




-i ' ' 




1973 



980 1981 1982 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 



Figure 2— World annual tungsten concentrate production (left) and consumption (right), 1973-82. 



I 1 1 1— 




1 I 4. 


i 


.. .. T 






/ -»*, 






- 




/ 

-, / ^ 


-> 
\ 


- 










*\~\ 


> 




/fT 




n\ " 


\ _ 




// 




\ \ 


\ /^ 




■ / / 

/ 




\ \ 


-\ \ /' 




^••J 




\ - 


x \ Aa 








\ 


N V 




KEY 




\ - 

\ 

\- 




- 




Consumption 












\ 


1 1 1 




i i i 


i 


J 



" ! 1 1 i i 


T 1 




— 1 






1 ^- 


^- — 




/ / 








/ / 

/ 
/. 






/r— — 


— J 






// 








// 






- 


/ 1 








^-— — ' ' 






_ 


^^^^ 1 








r"^ 1 






_ 


1 








1 








^____v 








i i i i i 


1 




1 



1977 1978 

YEAR 



Figure 3. — MEC (top) and CPEC (bottom) production and con- 
sumption of tungsten concentrate, 1973-82. 



pet of world production between 1973 and 1982, and pro- 
duced 21 to 29 pet of the world total over the same period. 
The excess production made China the most important 
world supplier throughout the period, while earning 
substantial amounts of foreign currency and enhancing the 
country's balance of payments position. 



Many factors affect the pattern of world production and 
trade. Export and import taxes, for example, may determine 
the location of tungsten processing facilities. Bolivia taxes 
the export of processed mineral products more heavily than 
ore and concentrate, a factor that probably accounts for the 
fact that a large percentage of Bolivian exports are in con- 
centrate form. Probably more common are tax incentives 
that encourage mineral processing facilities to locate within 
a country. The United States, for example, taxes the im- 
port of processed tungsten products much more heavily than 
the import of ore and concentrates. 

Another factor affecting world trade, but which is dif- 
ficult to quantify, is smuggling. It is likely, for example, 
that a substantial amount of production from Thailand is 
not officially accounted for and probably is illegally 
transported out of the country, but nevertheless enters the 
world market. These and other nontariff factors (e.g., im- 
port quotas) can add significantly to the delivered cost of 
tungsten ore, concentrate, or products, and affect world 
trade patterns. 

U.S. PRODUCTION, CONSUMPTION, 
AND IMPORTS 

Figures 5 and 6 show production, consumption, and im- 
port data for the United States for the 1973 to 1982 period. 
Production from U.S. mines (fig. 5) has been far below 
reported domestic consumption, averaging only 37 pet of 
consumption over the 1973 to 1982 period. Imports for con- 
sumption accounted for an average of 54 pet of U.S. con- 
sumption over the same period. Other sources of tungsten 
to the United States include scrap, and releases from the 
General Services Administration (GSA) stockpile of 
strategic and critical materials. 

Figure 6 is a graph showing U.S. imports of tungsten 
ore and concentrate, by exporting country, for 1973 to 1982. 
Bolivia, Canada, Peru, and Thailand have been relatively 
constant suppliers of sizable amounts to the United States. 
Mexico and Peru have been steady suppliers over the time 




LEGEND 
-•— 500 1 of tungsten 
<3= I.OOOt of tungsten 
C~\ 10,000 1 of tungsten 



Figure 4.— World tungsten trade pattern, early 1980s. 



KEY 



I I Shipments from U S Government stocks 
! ' U S imports for consumption 
V/A U S mine production 




period, but smaller amounts of imports from those countries 
do not show up during some years because of the cutoff 
levels used to make the graph. Australia and the Republic 
of Korea have been steady suppliers as well, but at levels 
too low to show up on the graph. Although the United States 
imported small amounts of tungsten from China in every 
year of the time period shown on the graph, since 1978, the 
country has been an increasingly important source. The 
lowest proportion was in 1973, when Chinese tungsten ac- 
counted for 1 pet of U.S. imports. China's share increased 
steadily through 1981, when a level of nearly 22 pet was 
attained. However, 1981 was an unusual year in terms of 
Canadian exports owing to the reduced output from Can- 
tung (because of a labor strike), that country's primary 
source of tungsten. Canada's 1982 share increased to a more 
historically typical level, at 32 pet of total U.S. imports. 



1978 1979 



Figure 5. — U.S. annual tungsten production, consumption, and 

import data. 1973-82. 




'977 I978 

YEAR 



Figure 6.— Sources of tungsten ore and concentrate imports to the United States, 1973-82. 



GEOLOGY AND RESOURCES 



A total of 57 MEC and 38 CPEC mines and deposits 
were analyzed for their tungsten resources. Additionally, 
the MEC deposits were evaluated for their cost of produc- 
tion using the Bureau's supply analysis model (SAM) 
economic evaluation methodology (4). Table 2 is a list of 
MEC depoeite analyzed, along with geologic type, owner- 
ship, and production status. 



EVALUATION METHODOLOGY 

Selection of deposits was based on discussions with the 
Bureau of Mines tungsten specialist, field center personnel, 
and personnel from the private sector. All major known 
primary tungsten deposits in MEC's were included, with 
at least 85 pet of known resources and 85 pet of current pro- 
duction capacity accounted for. 



Table 2.— MEC tungsten deposit information 



Location and deposit' 

California: 

Adamson 1 

Andrew 2 . . 

Atolia Placers 3 . . 

Pine Creek 4 . . 

Strawberry 5 . . 

Idaho: Thompson Creek 6 

Nevada: 

Emerson 7 . . 

Indian Springs 8 . . 

Nevada Scheelite 9 . . 

Pilot Mountain 10 

Springer 11 . 

North Carolina: Tungsten Queen ... ,12 . 

Australia: 

Kara 13 . 

King Island 14 . 

Mount Carbine 15 . 

Mount Mulgine 16 

Torrington 17 . 

Austria: Mittersill 18 . 

Bolivia: 

Bolsa Negra 19 . 

Chambillaya 20 

Chicote Grande 21 . 

Chojlla 22 

Enramada 23 

Kami 24 . 

Pueblo Viejo 25 . 

Tasna 26 . 

Viloco 27 . 

Brazil: 

Barra Verde 28 

Boca de Lage 29 

Brejui 30 . 

Zangarelhas 31 . 

Burma: Mawchi 32 

Canada: 

Cantung 33 . 

Logtung 34 . 

Mactung 35 

Mount Pleasant 36 

France: 

Montredon 37 

Salau 38 

Mexico: 

Baviacora 39 

Los Verdes 40 

San Alberto 41 

Namibia: 

Brandberg West 42 

Krantzberg 43 

Peru: Pasto Bueno 44 

Portugal: 

Borralha 45 

Panasquiera 46 

Republic of Korea: Sangdong 47 

Spain: 

Barruecopardo 48 

La Parilla 49 

Santa Comba 50 

Sweden: Yxsjoberg 51 

Thailand: 

Doi Mok 52 

Doi Ngoem 53 

Khao Soon 54 

Turkey: Uludag 55 

Uganda: Nyamalilo 56 

United Kingdom: Hemerdon 57 



Type 



Owner and/or operator 



Status 



Tactite . 
Talus . . 
Alluvial 
Tactite . 
... do 
... do 



... .do 

Tactite, stockwork 

. ... do 

Tactite 

do 

Vein 



Tactite . . . . 

do 

Veinlet . . . . 

do 

Sills, dikes 
Stratiform 



Vein-manto 
Vein 

. .do 

..do 
do ... 

. . do ... 

. . do ... 

. . do ... 

. . do ... 



Tactite . 
. do 
... do 
... do 
Vein . . . 



Tactite 

Vein, stockwork 

Tactite 

Porphyry 



Vein 
Tactite . 

do . . 

Porphyry 
Tactite . . 



do 



Vein 
. . . .< 
Vein . . 

Vein . . . 

do. 

Tactite . 



Porphyry 
Vein 

.... do . . 
Tactite . . 



Vein 

do 

.... do 

Tactite 

Stratabound vein . 
Veinlets 



Panaminas , . . . . 

Curtis Tungsten Inc 

H.W. Hobbs, Mines Exploration. Inc. 

Union Carbide 

Teledyne 

R.M. Barrett 



Teledyne, N. Tempiute, Union Carbide 

Utah International 

Natural Resources Development Inc. 

Union Carbide 

Utah International (GE) 

Ranchers Exploration & Development . 



Tasminex, Mclntyre Mines 

Peko-Wallsend Ltd 

Queensland Wolfram Ltd 

Minefields Exploration 

Barix Pty. Ltd 

Metallgesellschaft, Voest-Alpine 

Comibol 

International Mining Co 

Churquini Enterprises Inc 

International Mining Co 

.... do 

Comibol 

Sra. Eva Thiel de Sara 

Comibol 

do 



Mineracao Sertaneja Ltda 

Tungs do Brasil Min e Met 

Mineracao Tomas Salustino S.A. 

Tungs do Brasil Min e Met 

Burmese Government 



Canada Tungsten Mining Corp. . 

AMAX, Logtung 

AMAX Northwest Mining Co. Ltd. 
Billiton Canada, Sullivan Mng . . 



Bur Res Geol and Min, Penarroya 
Co Met and Min, L. O'mnivini des Min. 



Tungsteno de Baviacora SA 

Cia Minera Coronado S.A. de CV 
Draco 



SW Africa Ltd. (Goldfields) 

Nord Resources, Bethlehem Steel 
Fermin Malaga Y Santolalla 



Minas da Borralha Sari 

Serra d Estrela 

Korea Tungsten Mining Co. Ltd. 

Coto Minero Merladet S.A 

Minero Bonilla 

Coparex Minera S.A 

Luossavaara Kiirunavaara AB . . 



Sirithai Scheelite 

Parasit Mining Co 

Siamencan Mining Co. Ltd. 

Etibank 

Ugandan Government .... 
AMAX, Hemerdon Mining . 



P 

P 

PP 

P 

P 

PP 

P 

N 

P 

PP 

P 

PP 

P 
P 
P 

N 
N 
P 

P 
P 
P 
P 
P 
P 
P 
P 
P 

P 
P 
P 
N 
P 

P 
N 
N 
N 

PP 
P 

P 
N 
P 

PP 
PP 
P 

P 
P 
P 

P 
P 
P 
P 

N 

P 

PP 

P 

PP 

N 



N Nonproducer. P Producer. PP Past producer. 
'Numerals refer to sites on location maps (figs. 10-16). 



Cumulative 
production 



ECONOMIC 



MARGINALLY 
ECONOMIC 



SUBECONOMIC 



IDENTIFIED RESOURCES 



Demonstrated 



Measured 



Indicated 



Reserve 



base 



Inferred 



Inferred 

reserve 

base 



UNDISCOVERED RESOURCES 



Probability range 
(or) 



Hypothetical 



Speculative 



+ 
+ 



Other 
occurrences 



Includes nonconventional and low-grade materials 



Figure 7. — Classification of mineral resources. 



The evaluation of these 57 deposits was done on resource 
values sufficiently defined to be considered demonstrated 
according to the definitions established by the Bureau of 
Mines and the Geological Survey {5) "fig. 7). Although an 
attempt was made to acquire resource information at the 
inferred level, adequate data were generally difficult to 
obtain: thus, inferred resources are not addressed in this 
report. Demonstrated resource data were readily available 
for most MEC deposits, either from published sources 
| Bureau. U.S. Geological Survey, State, and industry 
publications; professional journals; and company annual 
reports and lOK'si and contacts with deposit owners, or from 
individuals and government agencies with personal 
knowledge of the deposit. All resources evaluated can be 
mined and beneficiated using current technology. 

Principal Chinese and Soviet (i.e., major CPEC tungsten 
producers ) deposits are included in the study, but were not 
subjected to cost evaluation owing to a general paucity of 
sufficiently documented resource data, and problems in col- 
lecting production costs and coverting costs to U.S. dollar 
equivalents. 



GEOLOGY OF TUNGSTEN DEPOSITS 

Tungsten occurs in three main types of economically 

important deposits: <1) contact metamorphic-metasomatic 

scheelite-bearing tactites, or skarns, <2) wolframite-bearing 

quartz veins, and (3) deposits of volcanogenic origin 

Tungsten also occurs in pegmatites, placers, brines, and 

ts associated with porphyries. 

Although about 20 tungsten-bearing minerals are 

n. tungsten mineralogy is quite simple, and the 

economically important minerals can be categorized into 

olframite and .scheelite. The wolframite group 



contains three ore minerals that form a continuous solid- 
solution series of iron-manganese tungstates, with ferberite 
(FeWO„) and huebnerite (MnWOj as end members, and 
wolframite [(Fe, Mn) WOJ as an intermediate member. The 
scheelite group contains only one economically important 
member, CaW0 4 , which accounts for about 50 pet of the 
world's known deposits (6, p. 182). 

In general, tungsten mineralization is genetically 
associated with felsic igneous rocks such as granodiorite, 
quartz monzonite, and granite. There is a strong associa- 
tion of tungsten occurrences with orogenic fold belts, par- 
ticularly the Mesozoic-Tertiary Alpine-Himalayan (e.g., 
Nanling Range, China) and Circum-Pacific systems (e.g., 
Bolivian Andes, North American Sierra Nevada); however, 
some tungsten is found in Precambrian shield areas of 
eastern Canada, eastern Brazil, Australia, and parts of 
Africa (7). 

Tactites, numerically the most common form of 
tungsten deposit, are formed through high-temperature 
replacement and recrystallization of calcareous sedimen- 
tary rocks at or near the contact with an igneous intrusion. 
They typically are located near to the higher parts of the 
intrusive. Tactites generally have distinct boundaries, but 
scheelite mineralization is usually erratically distributed 
throughout the ore body, and can range in size from small 
isolated pods to massive bodies. Although tactite bodies are 
frequently small and irregular in shape, the largest known 
tungsten occurrence, Shizhuyuan, China, contains an 
estimated 627,000 t of WO-, in limestone beds in contact 
with a granitic intrusion. Sulfide minerals often found in 
association with scheelite in tactites include pyrrhotitc, 
chalcopyrite, and sphalerite, commonly with a calc-silicate 
gangue. Important tactite deposit evaluated for this study 
include Sangdong in the Republic of Korea, Pine Creek in 
California, and Cantung in Canada. 



10 



Tungsten-bearing vein deposits are widely distributed 
geographically, and account for more than 60 pet of the 
world's reserves (8). The veins occur as discrete bodies, vein 
swarms, or stockworks, usually found in roof zones 
associated with acidic igneous intrusions. Tungsten is 
mainly present as wolframite, huebnerite, or ferberite, but 
scheelite may also occur. Associated minerals often include 
cassiterite, arsenopyrite, and bismuthinite. Mineralization 
is usually erratically distributed, but can occur as localized, 
isolated pockets along an extensive vein. Stockwork or 
veinlet deposits can be quite large. For example, Logtung, 
Canada, contains more than 195,000 t of W0 3 . The greatest 
commercial concentration of vein-type deposits is in the 
southeastern portion of China, where the famous 
Xihuashan Mine is located. Other well known vein deposits 
evaluated for this study include all of those in Bolivia and 
Thailand. Tungsten deposits associated with porphyries in- 
clude the tungsten-molybdenum property at Mount Plea- 
sant in New Brunswick, Canada, and Climax in Colorado, 
which produces tungsten as a byproduct of molybdenum 
mining. These deposits, although genetically related to ig- 
neous bodies, do not occur as tactites or discrete vein 
systems. They are typically quite large (e.g., Mount Plea- 
sant contains nearly 72,000 t of W0 3 ), and display zonation 
of mineral type. 

Two deposits of unique geologic character include Mit- 
tersill in Austria and Searles Lake, California. Mittersill 
is a stratiform deposit that appears to have been related 



to submarine volcanic activity. Searles Lake, one of the 
largest known potential sources of tungsten in the United 
States, is a brine deposit. 



MARKET ECONOMY COUNTRIES 

Table 3 and figure 8 contain demonstrated resource in- 
formation for the 57 MEC deposits evaluated. MEC's 
account for nearly 45 pet of the total amount of tungsten 
contained in deposits addressed in this study. 

Following is a discussion of deposits analyzed, by 
country, addressing geology, resources, and other signifi- 
cant information relating to assumptions used for this 
study. Where the term "reserves" is used, it was taken 
directly from the published article cited, and does not 
necessarily conform to the meaning of that term as defined 
by the Bureau of Mines and Geological Survey (5) (fig. 7). 
Some published resource figures cited in the individual 
country discussions differ slightly from figures used in the 
analysis (table 3). 

Australia 

Australia is one of the largest MEC tungsten producers, 
with an estimated 6.4 million lb of W0 3 produced in 1982 
(9). Over 90 pet of the country's production is from two 
mines, the King Island scheelite mine on King Island, 



Table 3.— MEC tungsten demonstrated resources used for analysis, January 1983 



Location and deposit 



In situ 

resources, 

10 6 t 



In situ 

grade, 

pet WQ 3 



Contained WQ 3 



2 pct 



Recoverable WQ 3 
In prod- 
uct, t 



pet 



Source 1 



Australia: 

Kara 

King Island 

Mount Carbine 
Mount Mulgine 
Torrington 

Total or average . 

Austria: Mittersill 

Bolivia: 

Bolsa Negra 

Chambillaya 

Chicote Grande . . . 

Chojlla 

Enramada 

Kami 

Pueblo Viejo 

Tasna 

Viloco 

Total or average . 

Brazil" 

Burma: Mawchi 

Canada: 

Cantung 

Logtung 

Mactung 

Mount Pleasant . . . 

Total or average . 

France: 

Montredon 

Salau 

Total or average . 



1.0 

7.6 
24.5 
37.0 

6.0 



4.8 
.6 



0.73 

1.03 

.10 

.19 

.20 



.68 



.53 
.50 



7,300 
78,280 
24,500 
70,300 
12,000 



.5 


1.04 


5,200 


.5 


.58 


2,900 


2.4 


.80 


19,200 


2.8 


.40 


1 1 ,200 


.5 


.80 


4,000 


.6 


.97 


5,820 


.1 


1.09 


1,090 


.4 


.84 


3,360 


( 3 ) 


1.50 


670 



53,440 



3.0 



25,440 
3,000 



1.5 
.2 



3,452 
34,177 
22,982 
42,642 

6,350 



76.1 


.25 


192,380 


11.0 


109,603 


9.1 


4.5 


.50 


22,500 


1.3 


15,787 


1.3 



1,562 

1,786 

12,485 

5,924 

2,568 

3,620 

897 

1,110 

279 



30,231 



16,214 
1,087 



2.6 


1.32 


34,320 


25,884 


163.0 


.12 


195,600 


154,202 


57.0 


.96 


547,200 


412,700 


26.5 


.27 


71,550 


45,871 



2.5 



1.3 

.1 



249.1 


.34 


848,670 


48.4 


638,657 


53.0 


2.0 
.9 


.63 
1.40 


12,600 
12,600 




6,841 
8,576 




2.9 


.87 


25,200 


1.4 


15,417 


1.3 



2, 3 
2, 3 
2 

1, 3 

2, 3 
2, 3 

1, 3 
3 

2, 3 



1, 5 
3 

2 
2 
2 
2 



2, 3 
2, 3 



See explanatory notes at end ot table. 



11 



Table 3.— MEC tungsten demonstrated resources used for analysis. January 1983— Continued 



Location and deposit 



In situ 

resources, 

101 



In situ 

grade. 

pet WQ 3 



Contained W0 3 



2 pct 



R>\ overable WO 
In prod- 
uct, t pet 



Source' 



Mexico 4 

Namibia: 

Braodberg West 
Krantzberg 

Total or average 

Peru Pasto Bueno 

Portugal. 
Borralha 
Panasquie-a 

Total or average 

Republic of Korea Sangdong 

Spam 

-ecopardo 
La Paniia 
Santa Comba 

Total or average 

Sweden Yxstoberg 

Thailand 
Dot Mok 
Doi Ngoem 
Khao Soon 



4.7 


0.45 


21.150 


1.2 


7.901 


0.7 


2.4 
.9 


.20 
40 


4.800 
3.600 




2.862 
2,099 




3.3 


.25 


8.400 


.5 


4,961 


.4 


1.0 


.46 


4,600 


.3 


3,055 


.3 


.7 

6.1 


.47 
.36 


3,290 
21.960 




1,364 

17,224 




6.8 


.37 


25,250 


1.4 


18,588 


1.5 


8.5 


.86 


73,100 


4.2 


61,098 


5.1 



20.9 


.08 


16.720 


6.2 


.19 


11.780 


36 


.50 


18.000 



30.7 



.15 



1 5 

1.0 

.4 

2.5 



.43 

0.75 
1.75 

1.00 



39 



1.01 



14.0 

0.9 

56.0 

936 



.50 
.24 
16 
.21 



570 7 



.31 



46.500 



2.7 



6,450 

7.500 

7.000 

25.000 



39,500 



2.3 



70.000 

2.160 

89.600 

196.660 



4.0 

.1 

5.1 

11.2 



1,754.000 



100 2 



5.726 
5.627 
8,923 



20,276 



5.384 

4.171 

2,151 

13,847 



Total or average 

Uludag 
Uganda Nyamalilo 
United Kingdom Hemerdon 
United States- 1 

Grand total or average 

'Resource data were obtained from the following sources 1 — Calculated from published dimensional data on ore body; 2- 
3 — Data provided by company, government agency, or person familiar with deposit. 
'Country total only. 
3 Less than 1 million t 
'Individual deposit data not provided owing to confidentiality of information See table 3 for deposit names. 



20,169 



35.372 

1,556 

55.020 

145.569 



1.205,945 



1.7 



1.7 



2.9 

.1 

4.6 

12.1 



100.1 



1. 3 

1, 3 
1, 3 
3 



■Published resource estimate available; 




Tasmania (60 pet of the total), and the Mount Carbine 
wolframite mine in northern Queensland. The remaining 
10 pet is from half a dozen small mines in Tasmania, 
Queensland, and the Northern Territory. The five deposits 
evaluated (fig. 9) account for 11.0 pet of the contained W0 3 
in MEC deposits evaluated. 



I 




^3^^— 






- 




/i 






1 


* f 

^ /it 




[<J »A 






O / 


NORTHERN 

1 




* 
111 

u 




wctTcm 




QUEENSLAND * 






AUSTRALIA 








SOUTH 






\ *" 


Australia 




Avy 








NEW SOUTH 




* 




e 


WALES 
llvtCTORiA\/ 


J *< 




WO 


DOS 


V/^TASMANIA 


tttft.l* 



Figure 8— Demonstrated contained W0 3 resources for MEC 
deposits evaluated. 



LEGEND 
*" DeponT l.tted iniobie*. 



Figure 9.— Location map, Australian deposits. 



12 



Production of tungsten concentrate at Kara began in 
August 1977 and intensive exploration commenced shortly 
thereafter. For purposes of this evaluation, full-scale pro- 
duction of 180,000 t (full capacity) by the mid-1980's has 
been assumed, although present production is half that. The 
deposit consists of four tactite bodies. The ore mineral of 
primary interest is scheelite. The tactite occurs in Cambrian 
and Ordovician carbonates that have been intruded by a 
Devonian granite. The assemblage is overlain by Tertiary 
basalts. The principal zone of interest lies within one of the 
four bodies, known as Kara No. 2, which consists of a system 
of densely packed mineralized lenses that coalesce in a 
blanketlike form. Grade of mineralization varies con- 
siderably within the zone, especially in the vertical dimen- 
sion. Demonstrated resources as of January 1983 were 
estimated to total approximately 1 million t averaging 0.73 
pet W0 3 (10, p. 200). 

King Island consists of two underground mines at 
Grassy, King Island, Tasmania. They are the Bold Head 
Mine, which commenced operations in September 1972, and 
the Dolphin Mine which began in June 1973. During the 
production year 1980 to 1981 they produced approximately 
250,000 1 units of W0 3 concentrate with an overall recovery 
of 81.9 pet from 408,124 t of ore averaging 0.76 pet W0 3 
(10, p. 200). 

The King Island ore occurs in contact metamorphics 
on the periphery of two small granitic intrusions, the largest 
of which is 6.5 km in diameter. The Bold Head deposit con- 
sists of several stratiform lenses that dip at 15° and are 
generally between 2 and 5 m thick, except in faulted areas 
where mineralization thickens to 15 to 20 m. The Dolphin 
is a separate ore body approximately 3 km from the Bold 
Head. It consists of a garnet hornblende lense 50 m thick 
dipping at 35 °, and continues under the seabed. It has been 
delineated to at least 300 m below sea level. The scheelite 
occurs as fine disseminated grains (average size 0.05 to 0.02 
mm) in and along the margins of the andradite garnets in 
the tactite. Reserves classified as "recoverable proven and 
recoverable probable" (not including dilution) at the two 
mines total 6.6 million t at a weighted average grade of 1.02 
pet W0 3 (10, p. 200). 

The Mount Carbine open pit mine in Queensland has 
been a major open pit producer of wolframite and scheelite 
concentrates since 1974, with 1981 production of 1,366.67 
t of wolfram from 1.86 million t of ore. Scheelite produc- 
tion was 416.7 t (10, p. 198). Proven reserves at Mount Car- 
bine were recently reported to total 28 million t grading 
0.1 pet WO ? (10, p. 198). 

Production is from a series of vein structures occupy- 
ing a 375- by 600-m area occurring in folded argillaceous 
metasediments and basic volcanics of Middle Devonian to 
lower Carboniferous age (Hodgkinson Formation), which 
have been intruded by granites. Widths of individual veins 
vary from 15 to 50 cm. Depth of mineralization has been 
confirmed by diamond drilling to persist to at least 300 m 
(11, p. 33). The mineralization is erratic, making assessment 
of grade difficult. 

Individual crystals or blocks of crystals of wolframite 
and scheelite occur in sizes ranging from microscopic to 1 
m. A common crystal size is 5 cm in length. The average 
ratio of wolframite to scheelite is 3:1. Other minerals 
present include cassiterite, molybdenite, arsenopyrite, 
pyrite, and chalcopyrite, none of which occur in economic 
amounts. 

The Mount Mulgine deposit is located in the southwest 
part of Western Australia. Molybdenite has been known to 



occur at Mount Mulgine Hill since 1914, and large, rela- 
tively low-grade tungsten resources were discovered in 
1971. Scheelite, molybdenite, fluorite, and chalcopyrite 
mineralization has been located in a small greisen zone at 
the margin of a succession of chlorite schist, chlorite- 
actinolite schists, and metasedimentary units, and in quartz 
veinlets associated with granitic dikes. Scheelite occurring 
in volcanic schists represents the bulk of mineralized 
tonnage in the deposit. 

Preliminary drilling has shown that resources amenable 
to open pit mining exceed 37 million t at an average grade 
of 0.19 pet W0 3 . The boundaries of the deposit are still open 
and it is expected that ultimate resources could be twice 
those reported (12). 

At the time of this evaluation, the Torrington project 
in New South Wales was in a standby status pending 
analysis and review of drilling results and formulation of 
management plans for the project's future. The property 
covers nearly 5,000 ha of mining and prospecting leases held 
by Barix Pty. Ltd., a subsidiary of Pacific Copper Ltd., and 
consists of a least 38 known deposits, 13 of which have been 
examined in varying detail. 

The tungsten mineralization at Torrington is contained 
within late magmatic stage silexite sills and dikes 
associated with an extensive acid porphyritic biotite granite 
(the Mole Granite) which encloses an isolated roof pendant 
of Permian mudstone, sandstone, and conglomerate. 
Wolframite occurrences are divided into two groups, bodies 
wholly within the granite and those associated with the 
silexite-aplite intrusive bodies. The ore-bearing rock is an 
unusual mixture of quartz and topaz, with little or no 
feldspar and minor amounts of lithium mica. The silexite 
ore is generally fine grained. Principal ore minerals are 
ferberite and native bismuth. Accessory minerals include 
monazite, beryl, zinnwaldite, gold, fluorite, silver, joseite, 
and torbernite. Sampling has reportedly shown interesting 
gold, tin, and topaz values that are being further evaluated. 
Although these commodities may become economically im- 
portant to the property in the future, they were not included 
in this evaluation. 

Ore resources at Torrington are extremely difficult to 
evaluate owing to a high "nugget" effect; consequently, the 
grade distribution of tungsten is quite erratic and variable, 
ranging from 0.1 to 1.0 pet, averaging 0.2 pet W0 3 . Deposit 
dimensions are also quite variable, with individual 
mineralized areas varying in size from approximately 
20,000 to 500,000 t. Total in situ demonstrated resources 
are estimated at 6 million t; however, resources at lower 
probability levels appear to be substantially larger (13). The 
evaluation done for this study used the demonstrated 
resource tonnage and average W0 3 grade. However, a well 
designed mining plan that exploits higher grade pockets 
of ore early in the mine life could show substantial improve- 
ment over the average cost values derived in this 
evaluation. 

Austria 

Mittersill (fig. 10) is the only major producer of tungsten 
in Austria, with 1.3 pet of contained W0 3 in MEC deposits 
evaluated. The scheelite deposit was discovered in 1967 as 
a result of geochemical prospecting. Exploration work on 
the deposit commenced in 1968 and extensive drilling and 
drifting was completed by 1973. The mine and mill began 
production in 1976. Current annual ore production is 



13 




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LEGEND 
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LEGEND 
A 44 Deposit listed in toble 4 



Figure 11. — Location map, South American 
deposits. 



Figure 10.— Location map, European deposits. 



400,000 t '250,000 t by open pit), for a total of 6,400 t of 
25 pet WO, concentrate. 

The deposits occur in a series of regionally metamor- 
phosed rocks of Paleozoic age, especially within volcanic 
tuffs of alkaline to intermediate composition. The scheelite 
depofT is divided into Ostfeld (eastern) and Westfeld 
'western' ore zones. Minable scheelite is concentrated in 
stratiform, lense-shaped ore bodies having an average width 
of 100 to 150 m, and several hundreds of meters in length. 
Maximum thicknesses of 20 m occur in the central portions 
of the lenses. The ore bodies dip at 25° to 55° to the north- 
west . The deposit is 2,000 m long by 1,300 m vertical depth. 
In the Westfeld, seven ore bodies are known, all dipping 
40 to 50 to the north. Demonstrated resources as of 
January 1983 have been estimated to total 4.5 million t 
averaging 0.50 pet W0 3 . 

Bolivia 

Bolivia has numerous small tungsten mines, from which 
an estimated 6.4 million lb of W0 3 was produced in 1982 
t9>. Bolivian deposits evaluated, all producers, include Bolsa 
Negra. Chambillaya, Chicote Grande, Chojlla, Enramada, 
Kami. Pueblo Viejo, Tasna, and Viloco (fig. 11). A particular 
problem in defining Bolivian resources is that many of the 
deposits are poorly explored, with drilling done only to block 
out reserves to be mined in the near future. Hence, the re- 
sources estimated in this evaluation, which total 3.0 pet of 
the contained WOj in the MEC deposits evaluated, may sub- 
stantially understate the country's tungsten endowment. 

Bolsa Negra is an underground mine, leased to a 
cooperative numbering nearly 400 workers, which has 
operated the mine since 1965. Current annual ore produc- 
tion is 60.000 t and there has been very little progress in 
mechanizing the mine or in controlling production tonnages 
and grades. 

i occurs as lenticular-shaped mantos. dip 



ping at 20°, within a hornfelsic unit. There are approx- 
imately 20 known mantos contained in an area 60 m wide 
and 800 m long. Currently, three mantos are in production 
on each of four levels, and continuation below the lowest 
level is considered most likely. Lateral limits of the 
mineralized structures have not been determined, and vir- 
tually no exploration or development work has been done 
in recent years beyond that necessary to maintain produc- 
tion. Total demonstrated resources have been reported to 
be 500,000 t averaging 1.04 pet W0 3 {14, p. 8). 

Production from Chambillaya began in 1912 on a small 
scale. The property was acquired in 1973 by International 
Mining Co. which has initiated a program for more 
systematic exploitation of the deposit. 

The mineralized veins that make up the Chambillaya 
deposit are essentially vertical and vary in width from 1 
to 80 cm, averaging 30 cm. Lengths vary from 30 to 50 m, 
with vertical dimensions usually greater than the horizon- 
tal. The tungsten mineral is ferberite. In order to meet 
acceptable market specifications, the arsenic and sulfur that 
are intimately associated with the ferberite must be re- 
moved from the tungsten concentrate. 

One of the four sections of the mine was in the process 
of being evaluated at the time of this analysis and the 
results were not known. Total in situ demonstrated 
resources as of January 1983 were estimated to total 
500,000 t at 0.58 pet WO a . 

At the time of this analysis, Chicote Grande was in the 
exploration stage; production was expected to reach full 
daily capacity of 1,000 t as an underground operation by 
1985. Small-scale surface mining of tungsten has occurred 
for at least 40 yr, but the recent work represents the first 
serious attempt to exploit the deposit on a commercial basis. 

More than 60 veins with widths in excess of 10 cm have 
been mapped in the 1.8-km main exploration crosscut. The 
only mineral of current economic interest is wolframite, 
which occurs as isolated crystals ranging in size from a few 
millimeters to 5 cm long in a gangue of quartz, pyrite, and 



14 



arsenopyrite. Apparently, neither lateral nor vertical extent 
of mineralization has yet been fully defined, but some of 
the main veins outcrop for several hundred meters 
distributed in a circular area 2 km in diameter. The deposit 
was reported to contain in excess of 4 million t grading 0.8 
pet W0 3 (15). For this study, 2.4 million t was assumed to 
be demonstrated. 

The Chojlla and Enramada Mines exploit separate 
portions of the same mineralized structure. Both are owned 
and operated by International Mining Co., an established 
Bolivian entity. Because each mine is operated as a separate 
and distinct operation, they have been evaluated separately 
for this study. Since International's acquisition of both prop- 
erties in 1973, both operations have been extensively mod- 
ernized and mechanized. 

The mineralized zone at Chojlla consists of more than 
30 parallel veins over an area of 450 m by 1,400 m as deter- 
mined at the Carmen haulage adit, the current lower limit 
of exploration and development. The veins have a 
longitudinal en echelon arrangement with horizontal lenses 
varying from 30 to 250 m long. Vertical lenses vary from 
20 to 100 m high. Depth of the mineralization is at least 
400 m (to the Carmen level), but actual extent has not been 
established. Demonstrated resources were reported to total 
only 800,000 t at 0.4 pet W0 3 (14, p. 8); however, according 
to available dimensional data, this figure appears to 
significantly understate the resource, and a figure of 2.8 
million t was used for this study. 

Production at Enramada is by open stope from more 
than 20 veins that vary in width from 1 cm to 1 m (average 
70 cm). The veins consist mostly of quartz, with wolframite, 
arsenopyrite, pyrite, sphalerite, pyrrhotite, tourmaline, 
muscovite, fluorite, and minor amounts of cassiterite. 
Scheelite is also found sporadically. Mineralization is con- 
fined to the veins, and much of the wolframite occurs in 
crystals up to several centimeters in length. The mineral- 
ized zone is approximately 800 m long by 30 m wide with 
a depth of 300 m at the Liliana haulage adit. In 1979, in 
situ demonstrated resources were reported to total 700,000 
t averaging 0.8 pet W0 3 (14, p. 8). The potential for addi- 
tional resources apparently is very high, probably at least 
sufficient to last another 20 yr at the expected 1985 design 
capacity of 185,000 t/yr. 

Kami is a major underground producer of Bolivian 
tungsten concentrate, despite the fact that the deposit is 
reported to be exploited in an inefficient and disorganized 
manner, with little technical or managerial control. It has 
been owned by Comibol since 1952, but has been leased to 
a mining cooperative since 1965. Mining is by very 
primitive manual methods, with hand sorting of broken ore 
and simple concentration devices. Current annual produc- 
tion of ore is on the order of 114,000 t. 

The deposit has separate tin- and tungsten-rich zones, 
with tungsten concentrated in a hornfels unit covering an 
area of 21.7 km 2 . Tin mineralization is in a distinct zone 
bordering the periphery of the tungsten zone. Each zone is 
mined separately by the cooperative. Only the tungsten-rich 
section was evaluated for this study. Within the tungsten 
zone, production is from two principal vein systems. In- 
dividual veins average about 30 cm in width. Depth of 
mineralization has not been accurately determined, but ex- 
tends to at least 850 m. 



Officially reported demonstrated resources as of 1979 
were 170,000 1 at 0.86 pet W0 3 (14, p. 8); however, the mine 
is still producing, and, for purposes of this study, it has been 
assumed that there is sufficient ore to support the current 
level of production through at least 1987. Wolframite is the 
principal ore mineral. Sulfide content generally increases 
with depth. As future production extends to depth, it will 
probably be necessary to use more sophisticated processing 
techniques to process ore with higher arsenic and sulphur 
content. 

Production at Pueblo Viejo commenced in 1914 with 
small-scale surface exploitation of outcropping veins. 
Underground mining by open stope methods through five 
adits began about 1970. Average annual ore production has 
increased from about 5,200 t in the early 1970's to nearly 
30,000 t in 1981. Under a recently completed program of 
mine development and improvement to the mill, production 
is expected to increase to around 36,000 t annually. 

Mineralization at Pueblo Viejo occurs in fractures 
within a dacite intrusive measuring 15 km by 8 km. The 
mineralized vien system is approximately 1,000 m long and 
200 m wide. Veins vary in width between 25 and 30 cm, 
but all are mined to a minimum width of 1 m. Vertical ex- 
tent of the vein system has not been defined, but recent 
development work on the lowest of three working levels has 
verified that ore extends to that level. On this basis, 
demonstrated in situ resources have been verified to be ap- 
proximately 100,000 t, sufficient to continue production 
until 1986. Of notable significance is the fact that the veins 
at the surface appear to be narrower and of lower grade than 
deeper in the mine, a factor that favors exploration at 
depth. 

Prior to 1979, Tasna was primarily a bismuth-copper 
mine, with only 30 to 40 t of tungsten concentrate produced 
annually. However, with the collapse of bismuth prices and 
rehabilitation of the wolfram section of the deposit in 1976, 
it has become a major Bolivian tungsten producer. Current 
annual production is approximately 115,000 t of ore. There 
are no known plans for expansion or improvement of the 
operation to increase reserves beyond those that presently 
are known and can only last through the 1980's. 

The total mineralized area around Tasna covers 30 km 2 , 
with separate vein systems rich in tin, bismuth-copper, and 
tungsten. Only tungsten is currently produced from 19 
stopes on six veins up to 50 cm wide, 300 m long, and 250 
m deep. Half of total production is from stoping on wider 
(at least 50 cm) veins, the remainder from miniblock caving 
on 40- by 60-m blocks with heights of 30 to 40 m. Block cav- 
ing is used on relatively low grade (less than 0.5 pet W0 3 ) 
stockworklike structures. All ore is floated to remove sulfide 
minerals. 

Known in situ resources in the tungsten section total 
only about 400,000 t at 0.84 pet W0 3 , and there are little 
data from which to verify additional resources at lower 
levels of confidence. A crosscut driven on one working level 
of the mine to explore the stockwork mineralization in- 
tersected a number of thin veins of a grade substantially 
below the present cutoff level. 

Viloco is an underground mine with separate tin and 
tungsten zones, resulting in two separate and distinct min- 
ing operations. Comibol owns the property, but the tungsten 
section is worked by a group of contractors who receive pay- 
ment only for final concentrate they deliver to Comibol. A 
few thousand tons is mined annually by simple, primitive 
methods. The deposit contains principally tin mineraliza- 
tion, but wolframite veins occur in what is known as the 



15 



Tras Cuarenta section located in close proximity to a 
granitic batholith. Host rocks are Lower Devonian quart- 
zite and slate. Two separate groups of wolframite veins, one 
consisting of T veins, the other 12, comprise the known 
resource. Veins dip at 60 to 75 \ with widths varying from 
a few centimeters up to 1.5 m. averaging 60 cm. They con- 
tain mostly quartz, with some arsenopyrite and'pvnte. and 
minor chalcopyrite. sphalerite, and jamesoiute. Only 
wolframite and small quantities of scheelite are recovered. 
The full extent of mineralization has not been 
determined, since exploration and development work has 
been very limited. Horizontal development of the vein 
system extends to a length of 100 m and a depth of 150 m. 
Based on the present degree of knowledge, the tungsten sec 
tion of Viloco has onlj 40.000 t of demonstrated resources. 
averaging 1.50 pet WO, <N. p. 6>; however, the potential 
for additional resources is considered to be good. 

Brazil 

Brazil is an important producer of tungsten, with 
estimated 19S2 output of 3.300 lb of W0 3 (9i. Properties in- 
cluded in this analysis are Brejui. Barra Verde, Boca de 
Lage. and Zangarelhas (fig. ID. all of which are contiguous 
sections of a single large tungsten deposit located 6 km from 
Currais Novos Together they contain 1.5 pet of total con- 
tained \V0 3 in the MEC deposits evaluated. 

From the original outcrop at Brejui Mine, which has 
been in operation since 1943. the ore-bearing unit occurs 
in a laterally i I set of uniformly plunging folds, the 

>f which dip at 10 to 15 . and extend about 3.6 km 
over a vertical range of 760 m. The ore zone is 
approximately 150 m wide and is comprised of two car- 
bonate beds averaging 20 m thick separated by 20 to 60 m 
of quartz biotite gneiss. The carbonates occur w ithin a thick 
sequence of interbedded schist and gneiss. Scheelite is the 
only economic mineral; although molybdenum is present, 
it is not recovered. 

Brejui is an underground mine. There was an open pit 
section that operated sporadically as recently as 1980. Barra 
Verde, the adjacent lateral extension of Brejui, has been 
producing an average of 180.000 1 annually since 1955. Boca 
de Lage has produced nearly 100,000 t/yr since 1977 and 
Zangarelhas is currently being explored, with production 
assumed for 19*7 for purposes of this study. The facilities 
at Brejui and Barra Verde are owned by separate companies 
and operated independently. Boca de Lage and Zangarelhas 
are both owned by a subsidiary of Union Carbide; therefore, 
it has been assumed for purposes of this study that assumed 
annual output of 105.000 t of Zangarelhas ore would be 
processed at the Boca de Lage concentrator, which would 
be expanded to accommodate the increased production. 

Total demonstrated resources for the entire deposit (all 
four properties) are less than 5 million t at a weighted- 
average grade of approximately 0.5 pet W0 3 . 

Burma 

Most of Burma's tungsten production is derived as a 
b> product of alluvial tin mining by a large number of small 
mines located along the 1 < r, not 

all production is reported and a considerable amount is 
probably illegally transported out of 'he country. Mawchi 
ifig. 1 2 1. located in K;i robably ai I for a 

ficant portion of Burr ion of 1.9 

million 




LEGEND 
A 53 Deposit listed in table <» 

Figure 12.— Location map, southeast 
Asian deposits. 

included in this study, with 0.2 pet of the total contained 
W0 3 in the MEC deposits evaluated. 

Prior to World War II, Mawchi was the second largest 
tungsten mine in the world, but the mine was effectively 
dost roved by Japanese occupation' forces during the war 
with a program of high-grading the deposit. Despite 
technical and financial assistance from the U.S.S.R., the 
mine has not reopened on a comparable commercial scale. 
Presently, mining at Mawchi by tribute operators is 
restricted to 1-m-thick veins in granites, the distance 
between veins averaging 3 m. The contact of the granites 
with country rocks produced a contact metamorphic (tac- 
tite) deposit in limestones, which has been mined out. 
Mineralization in the veins now being worked consists of 
scheelite, wolframite, cassiterite, and arsenopyrite in a 
quartz matrix that tends to be richest at the edges of the 
veins near their contact with the granite. 

Apparently very little systematic exploration has been 
conducted at Mawchi since prior to World War II and none 
currently is planned; thus, information regarding extent 
or magnitude of resources is lacking. As of January 1983, 
in situ reserves are approximately 0.6 million t grading 0.5 
pet W0 3 and 0.9 pet SnO.,. 

Canada 

Canada produced an estimated 8.3 million lb of WO:, in 
1982 (9), or 7 pet of the world total, and 15 pet of produc- 
tion from MEC's. Four Canadian deposits were evaluated 
for this study. They include Cantung in the Northwest Ter- 
ritories, Mactung on the Northwest Territories border, 
Logtung in the Yukon, and Mount Pleasant in New 
Brunswick ifig. 13). Together they contain 48.4 pet of con- 
tained WO, in the MEC deposits evaluated for this study. 
Of the four, only Cantung has produced. It. is now 
temporarily closed down, awaiting more favorable market 
conditions. 

Cantung originated as an open-pit operation in 1962, 
but underground development commenced in 1972 as a 
room-and-pillar operation. The major geological structure 
in the mine area is a north-northwost 1 rending sync-lino 
Mineralized metamorphic- aur< ing from a few to 

ind meters v\ ido on- found around granitic in- 
mm- intruding a series of Precambrian to Dpp< r Cam 
brianargil andcarbo diments. The intrusives 

are probably related to large Cretaceou batholith" 



16 




LEGEND 
A 34 Deposit listed in table 4 

Figure 13.— Location map, Canadian deposits. 

occurring southwest of the mine area. Only tungsten ore 
is mined. The scheelite occurs with minor chalcopyrite and 
massive pyhrrotite in quartz-calcite veinlets. Proven 
minable reserves at Cantung were reported to be 3 million 
t grading 1.32 pet W0 3 at the end of 1981 (16). 

The Logtung property, under option to AMAX Minerals 
Exploration, is located midway between Watson Lake and 
Whitehorse in the Yukon. In terms of contained tungsten, 
it is the second largest MEC deposit evaluated for this study, 
with defined geological resources totaling 163 million t 
grading 0.12 pet W0 3 and 0.052 pet MoS 2 (17, p. 73). 

The Logtung area is underlain by Mississippian 
sediments, which have been largely altered to hornfels and 
tactites by intrusions of Jurassic or Cretaceous age. The 
predominant skarn is light green and siliceous with poorly 
to well developed bedding. Less common pyroxene and 
garnet skarn occurs in narrow beds, often with abundant 
disseminated scheelite and powellite. Tungsten, and 
molybdenum mineralization occurs within three different 
systems. A stockwork of quartz veins and fractures centered , 
upon a large felsic dike contains 90 pet of the total 
molybdenum and 75 pet of the total tungsten. The higher 
grade zone measures approximately 700 m in diameter and 
extends to a depth of over 300 m. Quartz veinlets up to 5 
mm thick contain fine-grained molybdenite, scheelite, and 
powellite with accessory pyrite, pyrrhotite, sphalerite, 
garnet, fluorite, and beryl. The mineralization is concen- 
trically zoned in the stockwork with a core of molybdenite, 
minor scheelite, and powellite centered on the porphyry 
dike, an intermediate zone of scheelite, and an outer zone 
of minor sphalerite and scheelite. Ten percent of the total 
tungsten occurs as disseminated scheelite and powellite in 
skarn beds. Large quartz veins contain approximately 15 
pet of the total tungsten and 10 pet of the total molybdenum 
(17). 

As of May 1982, the project was still in the development 
stage. AMAX has completed engineering and mining 
simulation studies, metallurgical testing, cost estimates, 
and financial analyses. For purposes of this evaluation, 
Logtung has been modeled to come into production by the 
end of this decade. 

Mactung is located along the Yukon and Northwest 
Territories border. There were plans to bring it into pro- 
duction by the mid-1980's as a room-and-pillar operation 
of 350,000-t annnual capacity. As at Cantung, metalliza- 
tion occurs within carbonate sediments in contact with 
Cretaceous intrusives. In fact, mineralized units at Mactung 
are correlative with those at Cantung although at Mactung 
the units are gently dipping and not generally as severely 



deformed as they are in the Cantung area. The scheelite 
at Mactung is generally finer grained than that at Cantung. 
The Mactung ore body is composed of a lower ore zone of 
one horizon and an upper ore zone of three horizons. The 
two zones are separated by 78 m of barren hornfels. 

AMAX officials estimated reserves to be 57 million t 
grading 0.96 pet W0 3 , making Mactung the largest deposit 
(in terms of contained W0 3 ) evaluated in this study. These 
reserves include 4.5 million t in the lower zone, which could 
be mined by underground methods. Another option being 
considered is to initially mine the upper zone, which con- 
tains 7.3 million t of minable ore averaging 1.41 pet W0 3 , 
by open pit methods (18, p. 2). For purposes of this study, 
the mine was evaluated as an underground operation with 
initial "high grading" of approximately 15 million t of ore 
averaging 1.37 pet W0 3 . 

At Mount Pleasant, mineralization accompanied brec- 
ciation and fracturing of a silicified feldspar-quartz por- 
phyry referred to as the Mount Pleasant Volcanics. The por- 
phyry is believed to be Mississippian in age, and locally 
overlies a series of argillites (Charlotte Group) and granites 
(St. George). The extent of silicification is believed to be ap- 
proximately 1,800 by 900 m, generally affecting the por- 
phyry with only minor alteration of the sediments to the 
west. Extensive exploration has yet to be performed in this 
area. Mineralization in the silicified portion of the porphyry 
ranges from sparse disseminations to massive patches, 
lenses, and fracture fillings. Tungsten occurs as both 
wolframite and ferberite. Molybdenum sulfide would be 
recovered along with tungsten products. 

Two areas of molybdenum-tungsten mineralization are 
known to occur at Mount Pleasant, the North Zone and the 
Fire Tower Zone. The latter consists of three separate 
molybdenum-tungsten bodies called Fire Tower North, Fire 
Tower West, and Fire Tower South. Mineralization in the 
Fire Tower South area has been intersected in a few holes 
and is a promising exploration target. Undiluted 
demonstrated geological ore reserves for the Fire Tower 
North and West were reported to be 9.135 million t of 0.393 
pet W0 3 and 0.202 pet MoS 2 . The North Zone contains four 
poorly delineated molybdenum-tungsten zones, a bismuth 
zone, a deep tin zone, and six near-surface tin-base metal 
bodies. Possible and probable reserves were given as 11.5 
million t averaging 0.11 pet Sn, 0.24 pet W0 3 , and 0.10 pet 
MoS 2 , as well as 9 million t of 0.1 pet Bi (19). 

Wolframite and molybdenite can be satisfactorily 
recovered from the Mount Pleasant ore; however, it is ex- 
pected that recovery of cassiterite and bismuth will be dif- 
ficult (20, p. 113). For this reason, this property has been 
evaluated under the assumption that only wolframite and 
molybdenite will be recovered. 

France 

France, although not a major world tungsten producer, 
has two deposits, Salau and Montredon (fig. 10), that con- 
tain 25,200 t of contained W0 3 at the demonstrated level, 
or 1.4 pet of the total in the MEC deposits evaluated. 

The Montredon-Labessonie tungsten district, in which 
the Montredon Mine is located, contains approximately 
30,000 1 of W0 3 of which 800 1 was exploited between 1955 
and 1960 (21). The district occurs within Middle Cambrian 
micashists in a dome structure underlain by an orthogneiss 
massif. The mineralized vein field consists of two groups 
of veins, each consisting of thick (0.3 to 2.0 m) and thin (less 
than 0.3 m) veins. The thiclt veins are more regular_than 



17 



the thin veins. The field strikes northeast and dips 60° 
south. Wolframite is irregularly distributed and is 
associated with minor amounts of cassiterite, fluorite, beryl, 
and 0.01 pet sulfides, of which pyrite is the most abundant. 

The vein field in the Montredon Mine area has been ex- 
plored by mine workings over a length of 600 m and a width 
of 300 m. Total demonstrated in situ resources at the Mon- 
tredon Mine are 2 million t averaging 0.63 pet W0 3 . 

The Salau Mine has been in production since 1971. Mon- 
tredon, a past producer, is being evaluated by property 
owners as a possible open-pit operation, scheduled to recom- 
mence production in 1984. For purposes of this evaluation, 
it has been assumed that production would begin in that 
year. 

Mineralization at Salau occurs as three types: skarn bar- 
ren of sulfides characterized by low grades (0.2 to 0.4 pet 
WOji; sulfide-rich skarns of medium grade (averaging 0.9 
pet W0 3 >; and somewhat massive pyrrhotite in limestone 
intercalated within granite slabs with high grade (2 to 10 
pet WO,) (22). The ore zone occurs as a column-shaped struc- 
ture adjacent to granite between 1,320 and 1,600 m eleva- 
tion, with a horizontal length of 220 m and a width of 50 
m. The ore body is extremely irregular and the mineraliza- 
tion discontinuous. The ore is dispersed and broken into 
several overlapping but more or less separate lenses, so that 
each lens can be considered as an independent ore body. 
This also renders resource evaluation extremely difficult. 
The demonstrated resource as of January 1983 was 0.9 
million t containing 1.4 pet W0 3 . 

Mexico 

The three tungsten-bearing Mexican deposits evaluated 
for this study are Baviacora, Los Verdes, and San Alberto 
'fig. 14). All are located in the State of Sonora and contain 
1.2 pet of total contained W0 3 in the MEC deposits 
evaluated. 

The general geology of the Mexican tungsten district 
can be characterized as consisting of a thick sequence of 
volcanics overlying a sedimentary and metamorphic base- 
ment. The volcanic sequence is several hundred meters 
thick and is comprised of flows, tuffs, and breccias that 
originated from a series of north-northwest trending faults. 
The volcanics were intruded by acidic plutons emplaced dur- 
ing the Laramide Orogeny. Differential erosion has resulted 
in a series of ranges consisting of volcanic plugs and intru- 



sions flanking valleys floored with lava flows and sedimen- 
tary debris. Site-specific geology for the Sonoran deposits 
is difficult to obtain; however, it is known that tungsten, 
copper, and molybdenum mineralization at Los Verdes is 
associated with a granodiorite porphyry, while Baviacora 
and San Alberto are tactite deposits. Scheelite is the 
primary tungsten mineral at Baviacora and San Alberto. 
Wolframite is recovered at Los Verdes. 

Baviacora and San Alberto are small open pit operations 
with mining labor perfomed by "gambusinos," small groups 
of local laborers. Annual ore production totals only about 
30,000 t for each deposit, with very low productivity. For 
Los Verdes, which is a pilot operation producing only a few 
tens of metric tons of concentrate annually, it was assumed 
for purposes of this study that mining will initially be done 
with gambusinos until the late 1980's, when more 
mechanized operations would take over and production 
would be increased to 300,000 t/yr. Very little information 
is available concerning the Los Verdes operation; evidently, 
though, there are problems in attempting to treat the ore 
because of the fineness of the tungsten particles. For the 
San Alberto evaluation, it was assumed that annual pro- 
duction could increase to 200,000 t by 1985. 

As with geological data, resource information is 
extremely difficult to obtain for the Mexican properties, and 
confidential resource data for individual properties cannot 
be disclosed. Total demonstrated resources for the three 
deposits are estimated to be 4.7 million t at a weighted- 
average grade of 0.45 pet W0 3 , of which approximately half 
is at San Alberto. 

Namibia 

Two Namibian properties, Brandberg West and 
Krantzberg (fig. 15), were included in this study. Together 
they contain 0.5 pet of total contained W0 3 in the MEC 
deposits evaluated. Both are past producers, with dubious 
chances for resumption of production. For purposes of this 
evaluation, it has been assumed that production at both 
properties could begin in 1986 at an annual capacity of 
105,000 t. 

Brandberg West is a hydrothermal wolframite-bearing 
vein deposit, with veins ranging between 1 and 3 m wide 
and 100 to 300 m long, dipping at 65°. Remaining reserves 
are estimated to total 2.4 million t grading 0.20 pet W0 3 . 
Owing to poor mining methods, aggravated by rising costs 
and low metal prices, the mine closed in 1979. A large 




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18 



amount of new development work would be necessary in 
order to resume production. 

The Krantzberg deposit consists* of lenses of greisen 
material with dimensions of up to 1Q0 m long by 100 m 
wide. The lenses, mainly horizontal, are scattered and dif- 
ficult to prospect. Wolframite was the dominant ore mineral. 
Total remaining demonstrated resources are 0.9 million t 
grading 0.40 pet W0 3 . 

Peru 

Pasto Bueno (fig. ID produces 660 t annually of high- 
grade huebnerite concentrate, plus byproduct lead, zinc, cop- 
per, and silver, from the treatment of 150,000 t of ore. Pasto 
Bueno is a group of three underground operations, Consuzo, 
Huaura, and Huayllapon, all of which are owned by a 
private Peruvian company and are located in the District 
of Pampos, Pallasca Province, Ancash Department. The 
mines are located 0.2, 15, and 17 km, respectively, from the 
concentrator at Consuzo. The Pasto Bueno deposit accounts 
for 0.3 pet of contained W0 2 in the MEC deposits evaluated. 

The geology of the Pasto Bueno area is characterized 
by a Tertiary quartz monzonite stock that has intruded a 
sequence of Upper Jurassic to Lower Cretaceous slate, 
limestone, and quartzite. The mining district contains more 
than 25 mineralized veins located partly in the monzonite 
and partly within the sediments. Four of the veins are of 
major economic significance. There have been two major 
episodes of mineralization, of which the second produced 
the important economic deposits. Typically, the district 
displays a vertical mineralogical zonation, characterized by 
increasing sulfide content with depth. 

In situ resources as of 1983 were estimated to total ap- 
proximately 1 million t containing 0.46 pet W0 3 and 0.44 
pet Cu. 

Portugal 

Estimated 1982 W0 3 production from Portugal was 3.8 
million lb (9). The two Portuguese properties evaluated for 
this study, Panasquiera and Borralha (fig. 10), are owned 
by the Beralt group and contain 1.4 pet of total W0 3 con- 
tained in the MEC deposits evaluated. 

The Borralha deposit is situated within the same 
geologic complex as Panasqueira. Maximum concentrate 
production in recent years was 370 t in 1975. Sufficient 
resources to last through 1990 at the planned rate of 360 
t of concentrate per year have been indicated during 
development to the 160-m level. The veins are known to 
extend to greater depths but as of 1979 had not been drilled 
below 160 m. The mineralization is composed of 80 pet 
wolframite and 20 pet scheelite {23). Demonstrated reserves 
based on development drilling are 0.7 million t grading 0.47 
pet W0 3 . 

Panasquiera is the single most important tungsten pro- 
ducer in western Europe, with over 2,100 t of high-grade 
wolframite concentrate annually, as well as tin and copper, 
from approximately 520,000 t of ore. Mining has taken place 
since at least the 1890's, and there is evidence that the 
deposit was worked by the Romans and Moors. Owing to 
labor strikes in 1981, the mine's output was severely 
reduced and planned production was not reached in 1982 
(24, p. 490). 

The main mineralized zone is a complex vein system in 
phyllite within the contact zone of a granite complex that 
is located over most of northern Portugal and forms a tin- 



tungsten district that extends into Spain. The late Precam- 
brian phyllite has intercalations of graywacke and fine- 
grained quartzite, and lacks distinct bedding but has a well 
developed system of subhorizontal joints, which has 
controlled the emplacement of mineralization. 

The main ore-producing zone consists of overlapping 
subparallel quartz veins that dip 8° to 10°; the zone is 70 
to 80 m thick and has been worked over a strike length of 
500 to 1,000 m and a dip of more than 2,000 rn (25); however, 
present proven depth is estimated to be 150 m. Assuming 
50 pet waste material, there is on the order of 6.1 million 
t of in situ resources at an average grade of 0.36 pet W0 3 . 

Republic of Korea 

The Sangdong Mine in the Republic of Korea is a major 
world producer of scheelite in the form APT, artificial 
scheelite, high-grade natural scheelite, and tungsten metal, 
oxide, and carbide powder. The mine also produces 
byproduct bismuth and molybdenum. Sangdong was respon- 
sible for nearly all of the Republic of Korea's estimated 6.3 
million lb of W0 3 in 1982 (9) and contains 4.2 pet of the con- 
tained W0 3 in the MEC deposits evaluated. Sangdong is 
operated by Korea Tungsten Mining Co. Ltd., a 100-pct- 
government-owned entity. 

The largest percentage of ore-grade mineralization at 
Sangdong occurs in a single stratabound body, the Main 
Vein, 3.5 to 5 m thick, which is located in the folded quartz- 
rich Myobong Slate of Early Cambrian age. The mineralized 
portion has been traced for over 1,500 m along both strike 
and dip. It is located on the gently dipping southern limb 
of an overturned west-nortwest trending asymmetrical 
syncline. 

The fine-grained, disseminated scheelite of the Main 
Vein is associated with several distinct silicate mineral 
assemblages, which exhibit a well-defined bilateral zona- 
tion in the plane of the ore horizon. Ore grades decrease 
markedly from the inner mica-rich zone (average 1.5 to 2.5 
pet W0 3 ), through the hornblendic intermediate zone (0.3 
to 1.5 pet) to the diopside-garnet zone (less than 0.5 pet) (26). 

Demonstrated in situ resources are approximately 8.5 
million t averaging nearly 0.86 pet W0 3 and 0.13 pet com- 
bined bismuth and molybdenum. 

Spain 

Three Spanish properties, all producers, were evaluated 
for this study: Barruecopardo, La Parilla, and Santa Comba 
(fig. 10). Together they contain 2.7 pet of total contained 
W0 3 in the MEC deposits evaluated. 

Barruecopardo is owned by Coto Minero Merladet, a 
100-pct-family-owned company that controls the leases 
covering a large percentage of the Barruecopardo mining 
district. The district has been known about since the early 
1900's but mining activities were negligible until 1940. 

Mining is by open pit method. Scheelite, the most im- 
portant tungsten mineral in the deposit, and wolframite in 
many veinlets are located within a medium- to coarse- 
grained leucogranite. The deposit is relatively low grade, 
averaging approximately 0.1 pet W0 3 . Thickness of 
mineralized veins varies from 0.5 to 15 cm, although they 
may exceed 0.5 m. Dimensions of the remaining resources 
average 800 m long by 100 m thick by 90 m deep, with an 
estimated 20.9 million t grading 0.08 pet W0 3 as of January 
1983. 
The present open pit mine and mill operation at La Parilla 



19 



began in 1971. Scheelite is the primary ore mineral and 
is mined from a series of mineralized veins over an area 
of 150 m by 700 m. to a confirmed depth of 150 m. As of 
January 19S3. demonstrated in situ resources are estimated 
to total 6.2 million t averaging 0.19 pet WO,, and 0.03 pet Sn. 

Mining at Santa Coniba began in 1943. lasted until 
1963. and recommenced in 1968 under the ownership of 
Compania de Minera Santa Comba. In 1980. Coparex 
Miner., became the owner-operator and the mine wont 
through a recent expansion to extract S00 t d by 1983. 
Wolframite and cassiterite are recovered from seven veins 
with a thickness varying from 3 to 50 cm each. The vein 
system outcrops over an area of 15 km 2 and dips at 75°. 
Mineralization is highly erratic. 

Demonstrated resources are on the order of 3.6 million 
t grading approximately 0.50 pet W0 3 . 

Sweden 

Yxs E fig. 10> was exploited for its copper content 

at least as early as the 18th century, and after the deposit 
found to contain scheelite during World War I. it 
developed into a tungsten mine from the mid-1930's through 
1963. In 1972. it recommenced production and was taken 
over by Luossavaara Kiirunavaara AB iLKABi in 1974. The 
mine is the only major tungsten producer in Sweden, with 
650 t of concentrate produced annually. The deposit ac- 
counts for 0.4 pet of contained WO ;) in the MEC deposits 
evaluated. 

The Bergslagen area, in which Yxsjoberg is located, is 
characterized by a series of altered Precambrian (age— 1.8 
billion yr) volcanic and sedimentary layers. Regional tec- 
tonism convened the acid volcanics to coarse-grained "lep- 
tites." and most of the limestone was recrystallized, with 
the more impure carbonates altered to skarn. Subsequent 
erosion was followed by deposition of pelites and, later, two 
phases of granitic intrusions, followed by intrusions of basic 
dikes. 

The tungsten deposit is comprised of three ore bodies, 
Kvarnasen. Vanergruvan, and Finngruvan, all of which 
were originally one limestone layer that was folded into a 
syncline and anticline with an axial dip of 45° east. 
Scheelite is irregularly distributed in the ore bodies, with 
Vanergruvan containing the richest concentrations. The 
three bodies also vary in size and configuration, with 
demonstrated resources totaling approximately 1.5 million 
p. 367 1 grading 0.43 pet W0 3 (28, p. 520). 

Thailand 

Thailands first tungsten mining operations began dur- 
ing World War II in Mae Sarieng Province near the 
Burmese border. Many of the original mines continue to 
ite sporadically. The discovery of two major deposits, 
Doi Mok in northern Thailand and Khao Soon in the south 
(fig. 12), in the early 1970's resulted in the production of 
5 t of concentrate in 1975. when Thailand became th<- 
second largest producer among MEC's '29. p. 1.72). Owing 
to the unstable local political situation, however, produc- 
tion from both mines has been interrupted repeatedly since 
then. Following discovery of the Doi Ngoem 'fig. 12) 
ferbente deposit in 1977, the chaotic political conditions in 
the local mining area were repeated, and order has yet to 
be fully restored. 

umated production of WO, from Thailand in 1982 
totaled nearly 2 8 mii. approximately 2 pet of the 



world total (9). The largest individual producer was the Doi 
Ngoem field, which accounted for one-fourth of Thai pro- 
duction. Substantial amounts of tungsten are produced as 
a byproduct of tin mining. For example, in 1981, the Nok 
Hoog Mine produced 333,000 lb of W0 3 contained in con- 
centrate. The three deposits evaluated account for 2.3 pet 
of total contained W0 3 in the MEC deposits evaluated. 

The ferberite ore at Doi Ngoem occurs in quartz veins 
in metasedimentary tuffaceous sandstone and chert in con- 
tact with an underlying biotite-rich granite of Mesozoic age. 
At least three parallel veins, all bearing ferberite in 
crystalline vugs and disseminations, constitute the ore body. 
The major vein averages 20 m in width and extends for a 
strike length of approximately 1,500 m (where exposed at 
the surface). None of the veins has been traced at depth, 
and geological information is difficult to obtain. A spur of 
the main vein has been dislocated by a fault, suggesting 
a depth of at least 60 m. Based on this information, the 
major vein may contain up to 2.5 million t of ore grading 
between 1.5 and 2 pet W0 3 . However, only 0.4 million t 
grading 1.75 pet W0 3 is considered to be minable given the 
current small scale surface operation, which produces 9,000 
t of ore annually. 

Doi Mok is a tactite deposit containing coarsely 
crystalline scheelite, along with arsenopyrite and other 
minor sulfides of no economic significance. There are two 
areas of mineralization, one a 20-m-wide zone within a 
granite close to its contact with overlying sediments, the 
other within a limestone unit. The ore body has not been 
explored at depth and only 1 million t is estimated to be 
in the demonstrated category, grading 0.75 pet W0 3 . 

Given the unstable political situation at Doi Mok, 
possibilities for future development, mechanization, or ex- 
pansion are highly speculative; however, it is possible that 
the mine could become a viable operation by 1990, and for 
this study it has been projected that production on a 
relatively small scale (60,000 t/yr) will have begun by 1990. 

Khao Soon is possibly the largest tungsten deposit in 
Thailand. Based on general geological characteristics of the 
deposit, it could contain 10 million t averaging 1 pet W0 3 . 
However, as with other Thai deposits, drilling data are 
scarce, and demonstrated resources are estimated to be 2.5 
million t averaging 1 pet W0 3 . 

The deposit was apparently formed by multiphase 
deposition of mineralized solutions within fractures and 
faults, particularly along the crest of a north-south anticline 
caused by intrusion of a biotite-rich granite. Ferberite, often 
with associated stibnite, occurs in pockets and small veins 
in mudstone, hornfelsic quartzite, and phyllitic shale. The 
main fracture system strikes northwest-southeast. 

In 1976, the miners made an agreement with the Thai 
Government to sell all ore to Siamerican Mining Co., Ltd., 
which holds the lease at Khao Soon. Government police 
were stationed at the mine to prevent violence and restore 
order. Continued invasions, however, forced the mine to 
close in 1979, and it is inactive at the present. For purposes 
of this evaluation, it has been assumed that the operation 
will have resumed normal (full capacity) production by 1992. 

Turkey 

Turkish tungsten production is small, with only 250,000 
lb of WO, estimated 1982 production (9), but Etibank's 
Uludag Mine (fig. 10), the country's only major tungsten 
mine, is potentially a more significant world producer than 
its current level of production indicates. The deposit ac- 



20 



counts for 4.0 pet of total contained W0 3 in the MEC 
deposits evaluated. The combined open pit and underground 
mine and concentrator have a design capacity of 560,000 
t/yr; however, it was reported that difficulties were ex- 
perienced during commissioning of the mine and concen- 
trator early in 1977, and a firm from the Federal Republic 
of Germany was brought in for consultation (30, p. 47). Plans 
are to convert the plant from gravity to an all-flotation 
operation. For this study, it has been projected that full pro- 
duction will be reached by 1985. 

Uludag ore occurs both in veins in granitic rocks and 
as tactite mineralization. Within the granites, veins have 
been emplaced along bedding and shear planes. Scheelite 
occurs mostly in finely disseminated form concentrated in 
brecciated zones within limestones of Mesozoic-Tertiary age. 
The scheelite occurs in four zones lying stratigraphically 
above each other. The layers are irregular along the bed- 
ding plane, and average thickness of the entire ore-bearing 
sequence is 200 m, including barren zones between 
mineralized layers. 

The deposit contains 14 million t of demonstrated 
reserves. Average grade was estimated at 0.5 pet W0 3 (30, 
p. 47). 

Uganda 

Nyamalilo (fig. 15) is one of six stratabound tungsten 
deposits in the Kigezi District and is the only Ugandan prop- 
erty evaluated for this study. It has been operated inter- 
mittently for over 20 yr. Maximum production was reached 
during the Korean War, at approximately 100 t/d of ore, 
but output had dropped to 50 t by the mid-1970's. For this 
evaluation, a concentrate production of 300 t/yr by 1986 
(105,000 t of ore) by open pit has been assumed. 

The main mineralized zone at Nyamalilo consists of 
numerous thin quartz veins enclosed by carbonaceous 
metasediments. The veins vary from a few centimeters to 
more than 1 m thick and may persist for several hundred 
meters along the strike. Larger veins lie along the fractures 
of enclosing rocks, while small veins follow bedding and 
have been folded along with the rocks. Mineralization is 
simple, consisting of fractured glassy quartz, patches of 
kaolinite, and ferberite present as the variety reinite 
(ferberite pseudomorphous after scheelite). 

The low average grade (2.5 lb W0 3 per metric ton, or 
0.11 pet) (31, p. 101) results in an economically marginal 
operation, except during times of high ferrotungsten prices. 
For this evaluation, a mineralized area measuring 1,000 
by 50 m to a depth of 50 m was assumed, within which a 
demonstrated resource of approximately 0.9 million t 
grading 0.24 pet W0 3 was estimated. 

United Kingdom 

Hemerdon (fig. 10) is the largest known tungsten deposit 
in the United Kingdom, and accounts for 5.1 pet of total 
contained W0 3 in the MEC deposits evaluated. Its existence 
has been known for over a century, but several past at- 
tempts to exploit the deposit commercially have proven un- 
successful. In 1977, a 4-yr exploration and feasibility pro- 
gram was begun, and a pilot plant was erected in May 1980. 
A final decision whether to bring the project into produc- 
tion was pending at the time of this evaluation. For this 
analysis, it has been assumed that initial production at a 
rate of 1 million t/yr will begin in 1987, reaching full capac- 
ity at a rate of 1.9 million t in 1989. 



Mineralization at Hemerdon is largely contained within 
a dikelike body of granite approximately 650 m long, 150 
m wide, and 200 m deep. Country rocks into which the 
granite was intruded consist of Devonian metasedimentary 
siltstone, mudstone, and altered basic volcanics. The granite 
contains a large number of small quartz veins rarely ex- 
ceeding a few centimeters in thickness. Three main vein 
systems are present, and the overall effect is of a sheeted 
vein complex. All of the vein sets carry wolframite, chiefly 
as irregularly distributed coarse aggregates of bladed 
crystals. Minor quantities of cassiterite are also present. 
Major gangue minerals found in the concentrate are 
hematite and arsenopyrite, which decrease and increase, 
respectively, with depth of the deposit (32, p. 343 1. 

Extensive drilling has established a resource of 56 
million t averaging 0.16 pet W0 3 and 0.025 pet Sn (16). 

United States 

Twelve U.S. deposits that do or could produce tungsten 
as the primary product were evaluated for this study. 
Together, they account for 11.2 pet of total contained W0 3 
in the MEC deposits evaluated. Deposits evaluated include 
Adamson, Andrew, Atolia Placers, Pine Creek, and 
Strawberry in California; Thompson Creek in Idaho; Emer- 
son, Indian Springs, Nevada Scheelite, Pilot Mountain, and 
Springer in Nevada; and Tungsten Queen in North Carolina 
(fig. 14). Not included in the study was the Climax deposit 
in Colorado, which, although the world's seventh largest 
tungsten producer when at full capacity, was not evaluated 
because it produces tungsten as a byproduct of molybdenum 
mining. The deposit contains 375 million t of ore (16) at an 
average grade of 0.03 pet W0 3 . Also not included was the 
Searles Lake brine deposit in California, with an estimated 
77,000 t of W0 3 at concentrations that average 0.007 pet 
(6, p. 184). Although tungsten is not presently recovered 
from the Searles Lake brines, technology exists to produce 
it as a byproduct of soda ash operations. 

The Andrew Mine currently produces approximately 
375 t of over 40 pet W0 3 and 3,400 1 of low grade (1 pet W0 3 ) 
concentrate annually, from 180,000 t of ore in talus cones 
located in the rugged San Gabriel Mountains north of Los 
Angeles. The oldest and most abundant rock type in the 
area is massive Precambrian augen gneiss characterized 
by porphyritic dikes and sills, hornblende lenses, and in- 
terfingering schists. Near the head of Cattle Canyon, in 
which the lode, talus, and placer deposits covered by the 
claims owned by Curtis Tungsten (owner of the Andrew 
Mine) are located, the gneiss is underlain and, in some 
places, intruded by a Cretaceous quartz diorite. The Triassic 
Mt. Lowe granodiorite and migmatite are exposed 
southwest of the gneissic unit. All rock types host quartz 
monzonite and andesitic dikes in complex crosscutting rela- 
tionships. Scheelite was deposited in and along fracture 
planes as veinlets, pods, and fine disseminations and is 
locally associated with quartz, calcite, and limonite; epidote 
and grossularite are rare. 

The mineralized lodes average less than 1 m in width, 
and are presently traceable over only short distances. 
Because insufficient data currently exist to adequately 
evaluate the resources contained in the lode and placer 
deposits, only the talus cones, which are well exposed and 
are amenable to evaluation, have been included as 
demonstrated resources for this study. 

The Atolia Placers was the only placer deposit evaluated 
in this study. The district, in California, was worked for 



21 



gold as early as the lS90's. Tungsten-bearing veins were 
worked during the early 1900s. and placer mining of the 
Spud Patch iso named for the occurrence of potato-sized cob- 
bles of scheelite 1 took place during the First World War 
when tungsten prices were relatively high. The district has 
experienced intermittent production since then, and the last 
significant known activity was in 1960. 

The scheelite and gold placers of Atolia were derived 
from the heavily mineralized Randsburg- Atolia area. The 
placer channels begin in the Stringer District. Kern County. 
5 km northwest of the town of Atolia where the underlying 
rocks and alluviu: I and subordinate scheelite. 

The channels trend southeast and. near Atolia. contain 
relatively high scheelite and lower gold values. The deposits 
vary in thickness from 2 to 40 m and are composed mostly 
of sand-sized particles and angular fragments up to 5 cm 
in size. Three primary channels contain the majority of gold 
and scheelite. They include the Atolia-Moore Placer, the 
Spud Patch, and the Atolia Rand ior Baltic* Channel. 

Small amounts of scheelite were produced from what 
is now known as the Emerson Mine as early as 1937, and 
the mine has produced continuously since then, except for 
the period 1958 through 1977. The scheelite-bearing tac- 
tites occur in two nearly parallel zones along the contact 
between a domed granitic stock and altered limestones and 
hornfels of the Guillemette Formation. The zones are re- 
ferred to as the Moody Tactite and Grubstake Tactite, which 
are separated by 15 to 20 m of coarsely crystalline mar- 
bleized limestone. The Moody Tactite has a surface strike 
length of 2,000 m, which increases with depth. Thickness 
varies from 5 to 32 m, over a known vertical depth of at 
least 500 m. The Grubstake is not persistent, but is known 
to exceed 30 m in thickness in some places. 

The Indian Springs deposit in the Delano Mountains, 
Elko County. NY. is an irregularly shaped body on the 
southeast side of an elongate Cretaceous quartz monzonite 
stock in contact with Permian calcareous sandstone of the 
lower Pequop Formation. The sandstone is cut by numerous 
quartz veins forming a stockwork associated with low-grade 
tungsten mineralization. Minor tactite deposits, irregularly 
distributed along the igneous contact, occur as pods and 
lenses associated with quartz stockworks. 

Results from 10,668 m of drilling in 149 locations in- 
dicated a reserve of 39.5 million t at an average grade of 
0.164 pet WO, Included in this are 12.6 million t averag- 
ing 0.265 pet \V0 3 i.33k 

The Nevada Scheelite deposit w r as discovered in 1930 
and was worked for precious metals for a short time, w ith 
the first reported production of tungsten in 1937. The mine 
has operated nearly continously through the present time. 

In the vicinity of the mine, scheelite-bearing tactites 
occur in metamorphosed limestone and hornfels at or near 
contacts with a small granite intrusive of Late Cretaceous 
or Tertiary age, and probably related to the Sierra Nevada 
Batholith. The intrusive crops out over an area of 4 km 2 . 
The limestone unit is approximately 150 m thick and has 
interbedded tuffs, andesites. and basalts. The granite con- 
tact is generally sharp and concordant with country rocks. 
Relatively large tactite bodies, up to 15 m thick, were 
formed along a major fault, while smaller bodies (av< 
ing 3.5 m thick* developed where fingers of granite 
penetrated the limestone along bedding planes. Tactite 
bodies are irregularly shaped where associated with th<- 
fault, but tend to be tabular alon^ concordant contacts. 

The Pilot Mountain deposits, in Nevada, were 
discovered in the 1920s, with first production in 1929, and 



sporadic production through the mid-1950's. The last re- 
corded production was in 1956. In the late 1970s, the prop- 
erty was acquired by Union Carbide, which has recently 
completed a detailed exploration program. 

Scheelite deposits at Pilot Mountain occur in a series 
of metamorphosed limestones of the Liming Formation, 
which has been tectonically disturbed by the intrusion of 
a granodiorite porphyry. The original mine workings occur 
along the granodiorite-limestone contact, where three types 
of mineralization are known to exist: ( 1 1 tactite. (2) a quartz- 
calcite-scheelite vein, and (3) irregular masses consisting 
of quartz, calcite, galena, scheelite, and silver. The largest 
tactite body occurs as a shallow dipping ( 10°) bed that ex- 
tends 150 m from the contact. 

Pine Creek and Adamson are adjacent properties cover- 
ing a series of tungsten-bearing bodies in the Bishop 
Tungsten District, Inyo County, CA. The Pine Creek mine 
and mill are owned by Union Carbide. The Adamson claims 
are owned by Panaminas, Inc., which leases them to Union 
Carbide, and production is reported as a combined total. The 
Pine Creek custom mill also treats concentrates from 
several other smaller mines in the region. Tungsten pro- 
duction from Pine Creek has been nearly continuous since 
1946. 

The Bishop deposits occur in a scheelite-bearing garnet- 
diopside tactite situated along ' the contact between 
Tungsten Hill Quartz Monzonite and limestone and horn- 
fels of the Pine Creek roof pendant, which strikes approx- 
imately north-south for 11 km. The sediments form the west 
limb of a south-plunging syncline. The tactite dips at a con- 
sistent 68° to the east over a strike length of several hun- 
dred meters. Scheelite is the major ore mineral, but 
powellite is also present, , along with molybdenite, 
chalcopyrite, bornite, gold, and silver. 

The Springer (formerly the Nevada Massachusetts 
Mine) scheelite deposit is located on the eastern slope of the 
Eugene Mountains, which trend north-northeast for 26 km 
near Mill City, NV. Tungsten was discovered in 1914, and 
production commenced shortly thereafter, with intermittent 
activity since then. The mine's most prosperous period was 
during 1950 through 1958, wdien ; as part of the Government 
program to build up a strategic stockpile, over 1 million t 
of ore was produced. The deposit is now owned jointly by 
General Electric and Utah International, under whom pro- 
duction resumed in early 1982, but was suspended later that 
year. 

The tactites of the area occur in metasedimentary rocks 
of the Raspberry Formation, Triassic to Jurassic in age. 
Locally, the Raspberry is composed of shale and thin-bedded 
limestone, and has been intruded by a series of Late 
Cretaceous granodiorite stocks. Principal concentrations of 
scheelite occur near the margin of at least one of the in- 
trusives, known as the Springer Stock. A dozen or more 
limestone beds ranging in thickness from less than 0.3 m 
to 9 m occur in the mine area. They have been cut by the 
northwest trending Stank thrust fault, the major structural 
feature of the area. Past and present production is from 
three main tungsten-hearing zones northeast of t he fault, 
where the Springer Stock is located. 

Strawberry is a producing underground mine in Califor- 
nia. It was discovered in 1941, and produced nearly con- 
tinuously through 1966. After an extensive drilling program 
in the early 1970s. Teledyne acquired the property and 
imed producl ion in 1978. 

The deposit is located iii a sequence of Lower Jurrasic 
calc-silicate hornfels and marble occurring as a roof pen- 



22 



dant surrounded by a Middle Cretaceous granodiorite 
pluton. Tactite deposits resulting from contact metasomatic 
replacement of marble occur within 100 m of the grandiorite 
contact. Two major bodies of tactite occur on opposite sides 
of a major anticline plunging 50°. The bodies dip steeply, 
and have an average length on the order of 130 m, an 
average downdip extension of approximately 75 m, and an 
average thickness of 3 to 4 m. The deposit is of relatively 
high grade, with a cutoff grade of 1 pet W0 3 (6, p. 181). 

The Thompson Creek Mine is located in the Bay Horse 
mining district of central Idaho, 3.5 km northwest of the 
Cyprus Mines Thompson Creek molybdenum project. The 
deposit was discovered in 1953, and has experienced inter- 
mittent production through 1977. It was formed by the in- 
trusion of the Cretaceous Idaho Batholith into limestone 
beds of the Paleozoic Wood River Formation. Two tactite 
bodies occur at the contact between the quartz monzonite 
of the Batholith and the limestone. Almost all the tungsten 
occurs as disseminated scheelite and ferberite, with minor 
powellite. The ore bodies extend for less than 200 m in 
length, average on the order of 3 to 5 m in thickness, and 
dip at 80°. Total known resources are limited, and are suf- 
ficient to produce only through the end of the decade from 
the 1984 startup date assumed for this study. The poten- 
tial for discovery of substantial additional resources is ap- 
parently limited. 

The Tungsten Queen Mine (formerly the Hamme Mine), 
in Vance County, NC, began operating in 1942; it last pro- 
duced in 1971. Tungsten occurs in randomly distributed 
quartz veins within a schist and granite-gneiss complex. The 
mine consists of one main vein (and several smaller veins) 
that strike northeast and dip 70° to the east. Ore occurs 
as numerous lenses within the veins. Extent of the 
mineralized zone is approximately 3,500 m long, nearly 600 
m wide, and 10 m thick. However, entire sections of some 
veins are mined out. The principal ore mineral is 
huebnerite, but some scheelite and minor sulfides also 
occur. 

Although a small amount of development work would 
be needed to reactivate the mine, it was reported that 
Ranchers Exploration and Development Corp., the owner, 
has decided to write off the $7.7 million investment (18, p. 
20). However, for purposes of this evaluation, the operation 
has been modeled to begin producing again in 1986 at an 
annual mine capacity of 150,000 t. 



CENTRALLY PLANNED ECONOMY COUNTRIES 

CPEC's contain over 55 pet of the world tungsten 
resources in deposits addressed in this report. China and 
the U.S.S.R. account for 93 pet of CPEC reserve base as 
estimated by the Bureau (9). A total of 38 deposits, 19 each 
in the U.S.S.R. and China, were evaluated for their resource 
potential. Pertinent information on CPEC deposits 
evaluated is shown in table 4. Only tungsten grades are 
shown, although many of the deposits do or would produce 
byproducts and/or coproducts. Because much of the infor- 
mation used to derive the estimates is highly speculative 
and incomplete, the resources cannot be considered as 
demonstrated. 

China 

China is the world's largest producer of tungsten, with 
estimated 1982 output of 31.5 million lb of WO, (9). Western 



observers believe that China could easily produce 20,000 
to 25,000 t of concentrate annually with the necessary lead 
time, of which 10,000 t could be exported (34). 

China is widely known to have the world's largest 
resources. One estimate places proven and probable (i.e., 
demonstrated) reserves at 1.2 million t (2.6 billion lb) of 
W0 3 , and potential reserves at nearly 2.4 million t (greater 
than 5 billion lb) (35, p. 75). National reserves have been 
officially reported to be 4 million t of W0 3 , or on the order 
of 8.8 billion lb of W0 3 (36, p. 436). The Bureau estimated 
China's reserves to be 3.8 billion lb of W0 3 , and total 
resources on the order of 10 billion lb (8, p. 983). 

Tungsten occurrences in China have been known about 
for many years. For example, Xihuashan, perhaps the best 
known Chinese deposit, was discovered in 1908. China came 
into world prominence in the years preceding the First 
World War, when most mining was done using hand labor 
and primitive techniques. Modern expansions and relatively 
advanced mechanization were not introduced until after the 
mines were nationalized in 1949. The first mechanized 
tungsten concentrator was erected and brought on stream 
jn 1952 at Tajishan in southern Jiangxi Province. 

Practically all known Chinese tungsten deposits are 
located in the Nanling Range in the southern part of the 
country. It is a rugged mountain chain trending southwest- 
northeast from southeastern Yunnan Province through 
northern Guangxi, northern Guangdong, and southeastern 
Hunan, to southern Jiangxi and Fujian Provinces. Complex 
folding and fracturing of sediments (contained in what was 
originally the Jinning-Caledonian Geosyncline during the 
Jinning, Caledonian, Hercynian, Indosinian, and Yensha- 
nian tectonic episodes), along with extensive magmatism, 
particularly the Yenshanian granitic intrusions, provided 
exceptionally favorable conditions for the generation and 
emplacement of tungsten deposits. The metallogenic episode 
occurred during the Jurassic-Cretaceous period. 

Chinese tungsten deposits can be categorized into five 
types: quartz vein, skarn, disseminated, stratiform, and 
placer. Many of the vein type deposits, currently the most 
important economically, are located in Jiangxi Province. 
A typical large Jiangxi mine in the Tayu District has hun- 
dreds of steep veinlets occurring over a mineralized area 
of several square kilometers, with reserves of possibly 
100,000 t of W0 3 contained in ore assaying 1.2 pet W0 3 and 
0.5 pet Sn. Mining at depths of 100 to 250 m is well 
engineered and at least semimechanized, and daily ore pro- 
duction is in the 2,000-t range (37). Xihuashan is a typical 
Jiangxi hydrothermal vein deposit, in which quartz veins 
and stringers have replaced or filled fractures in granite 
over a 4.5-km 2 area. More than 500 mineralized veins are 
known, every one of which contains visible W0 3 . They are 
remarkably persistent but narrow, with an average length 
of 200 m (maximum 800 m) and widths varying from 1 cm 
to 1 m, generally spaced 3 to 8 m apart. Dips are from 75 ° 
to vertical and, in addition to wolframite, contain 
cassiterite, bismuthinite, molybdenite, and other minor 
sulfides (38, p. 93). 

The Shizhuyuan deposit in Hunan Province is widely 
recognized as the world's largest known tungsten occur- 
rence. It is characterized by stockwork greisens super- 
imposed upon tactite situated at the contact between a Yen- 
shanian granite intrusive and argillaceous limestone and 
dolomitic limestone of Devonian age. It was reported to con- 
tain 190 million t of ore grading 0.33 pet W0 3 , 0.115 pet 
Sn, 0.122 pet Bi, and 0.06 pet Mo (36, p. 436). 



23 



Table 4.— CPEC in situ resources, January 1983 



Location and deposit 


Resource. 

103 t 


Grade, 
pet W0 3 


Contained 
W0 3 . t 


Geologic type 


Status 


Source' 


China: 

Bai Sha Po 

Dalongshan 

Damingshan 

Dangping 

Guimeishan 

Huangsha 

Hungshuichai 

Pangushan 

Piaotang 

Qmghu 

Shangping 

Shtzhuyuan 

Tajishan 

Wengyuan 

Xialong 

Xiangdong 

Xihuashan 

Yaokanghsien 

Yochang District 

Total or average 


47.042 

1.135 

13.962 

2.749 

2.175 

3.294 

1.274 

1.528 

2.432 

78.000 

695 

190.000 

3.890 

359 

851 

2.290 

17.428 

235 

488 

369.827 


0.15 

1.00 

1.04 

88 

2.20 

1.75 

.77 

1 90 

1.75 

38 

1.15 

.33 

.65 

1.90 

93 

72 

.65 

82 

1 90 

42 


70.563 

11.350 

145.205 

24.191 

47,850 

57.645 

9.810 

29.032 

42.560 

296,400 

7,993 

627,000 

25.285 

6.821 

7,914 

16.488 

113.282 

1,927 

9,272 

1.550.588 


Tactite vein 


D 


3 


Vein 
Stockwork. vein 

Vein 

do 


P 
P 
P 
P 


1 
3 
1 
1, 2 


do . 

do 

do 

Vein, stockwork 

Porphyry 


N 
N 
P 
P 
D 
P 
D 
P 
P 
P 
P 
P 
P 
P 

P 


1 
1 

1, 2 
1, 2 
3 


Vein 

Stockwork, tactite 

Vein 


1. 2 

3 

2 


do . . . 

do 

do 

. . . .do 

do 

do 

Greisen 


1, 2 

4 

4 

1, 2, 3 

4 

1 


USSR 


2.741 

1.179 

386 

1,181 

4.320 

400 

958 

10.910 

2.866 

1.505 

204 

475 

540 

5.000 

1.000 

50.800 

1.400 

22.025 

1.432 


.50 

80 
60 
60 
.60 
1.00 
.60 
.43 
.43 
80 
80 
60 
50 
.40 
50 
60 
45 
58 
60 


13.705 

9.432 

2.316 

7.086 

25.920 

4.000 

5.748 

46.913 

12.324 

12,040 

1.632 

2.850 

2,700 

20,000 

5.000 

304,800 

6.300 

127.745 

8,592 


1 


Antonova Gora 


Vein 


P 


3 


Vein, tactite 


P 


1. 2 


Belukha 


Vein 1 . 


P 


1. 2 


Boguty 


Vein, stockwork 

Vein 


N 
D 


1 
1, 2 


Bukuka 
Dzhida Field 
Ingichinsk 
lul'tin 


Vein, stockwork 

do 

Tactite 


P 
P 
P 


1. 2 
1. 3 

1 


Vein 


P 


3 


Kara Oba 

Kti-Teberda 

Lyangar 

Maykhunnsk 

Spokomyi 

Tyrny-Auz 

Verk -Keyraktm 

Vostc-2 


... .do 

do 

Tactite 

do 

Greisen 


P 
N 
P 
D 
N 


1 
1 
4 

1 
4 


Tactite 


P 


1. 2 


Vein 


P 


4 


Tactite 


P 


1 


Yubilennoye 


do 


P 


1 


Total or average 


109.322 


.57 


619.103 




Grand total or average 


479 149 


45 


2.169.691 





D Developed N Nonproducer P Producer 

'Resource data were obtained from the following sources 1— Calculated from published dimensional data on ore body; 2— remaining tonnage calculated 
from assumed or known past production; 3— published resource estimate available; 4 — estimate based on capacity and/or assumed life of operation 



U.S.S.R. 

Although it is the world's second largest producer, with 
an estimated 1982 output of 24.6 million lb of WO, (9), the 
U.S.S.R. continues to be a net tungsten importer. Principal 
tungsten producing regions are the North Caucasus, 
Kazakhastan. Uzbekistan, Transbaykal, and the Soviet Far 
East '24. p. 458 1. Deposits analyzed for this study contain 
nearly 1.4 billion lb of W0 3 . 

Tungsten deposits of the U.S.S.R. are of three main 
types: contact metamorphic (tactites), greisen, and vein- 
stock work. Pegmatites and placers are of relatively minor 
importance. 

Of the deposits classified as contact metamorphic, those 
at Tymv-Auz are undoubtedly the most significant, 
ated to contain nearly half of the total tungsten in the 
19 Soviet deposits examined. The Tyrny-Auz tungsten- 
molybdenum mine, a combined surface and underground 
operation, has produced since 1934 and is the main producer 
of tungsten in the U.S.S.R. The deposit consists of 20 steeply 
dipping orogenically related ore bodies that are worked 
along a 1.600-m front to a depth of 900 m (39, p. 104 1. 



Scheelite and molybdenite minerals are embedded in 
garnet-pyroxenes, calcareous and sulfide skarns, pyroxene- 
plagioclase and biotite hornfels, and marbles. 

A characteristic feature of greisen deposits is their ob- 
vious spatial and genetic association with acidic leucocratic 
and often pegmatitic granites. The tungsten-molybdenum 
deposit at Akchatau in Central Kazakhstan in the northern 
part of the Dzhungar-Balkash geosyncline is an example. 
There, Lower Silurian sandstone, siltstone, and argillite 
have been folded and intruded by a post-Early Permian in- 
trusive complex, the Akchatau granite massif. The deposit 
consists of 22 separate greisen bodies, or "clusters," over 
an area of 70,000 m 2 (40, p. 194). The deposit is one of the 
largest in Kazakhstan, with estimated resources of nearly 
14,000 t of contained W0 3 . 

Among the hydrothermal tungsten ore deposits of the 
U.S.S.R., the following varieties, with examples of each from 
deposits evaluated, have been identified: quartz-cassiterite- 
wolframite (lul'tin), quartz-scheelite (Boguty), quartz- 
wolframite (Antonova Gora, Bom-Gorkhon), and quartz- 
sulfide-tungsten (Bukuka, Dzhida Ore Field). 



24 



MINING AND POSTMINE PROCESSING TECHNOLOGY 



The geologic occurrence and nature of tungsten 
mineralization usually dictate the mining method. Dif- 
ferences in mineralogy and market considerations deter- 
mine beneficiation, intermediate, and final tungsten prod- 
ucts. Table 5 lists the MEC mines and deposits evaluated 
in this study, their status, capacity, mining and beneficia- 
tion methods, and primary tungsten product. Figures 16 and 
17 contain resource and mine capacity data by status and 
mine type for MEC deposits evaluated. 



MINING METHODS 

Many of the smaller deposits evaluated in this study 
are or would likely be mined simply by following 
mineralized outcrops from the surface to some depth, 
without great regard for grade control, productivity, or 
future mine planning. This approach is widely practiced in 
Bolivia, Burma, Mexico, Thailand, and several other less 
developed countries. For larger deposits in more in- 
dustrialized countries, the mining method depends upon 
depth and geometry of the ore body, competency of the ore 



and country rock, ore grade, development of a mine plan, 
and required capital investment. 

Surface 

Placer mining methods are utilized to recover tungsten 
from alluvial and eluvial deposits. The Atolia Placers in 
California, a small intermittent producer, was the only 
tungsten placer evaluated in this study. It was evaluated at 
an annual capacity of 1.3 million t of gravel using front-end 
loaders and trucks. The Andrew Mine, a small tungsten pro- 
ducer in California, is currently mining talus material using 
front-end loaders at an annual ore capacity of 181,000 t. 

Nineteen of the deposits evaluated (accounting for 29 
pet of total capacity) in this study are or would likely be 
mined exclusively by surface methods. The size, efficiency, 
and degree of mechanization vary widely. Open pit opera- 
tions like those in Mexico, for example, use a minimal 
amount of mechanized equipment and depend largely on 
pick-and-shovel methods. Labor consists of gambusinos, 
small groups of contract miners. Productivity at these labor- 
intensive open pit mines is relatively low, approximately 



Table 5. — Mine ore capacity, mining and beneficiation methods, product, and status 



Location and 
deposit 



Average 

capacity, 

103 t/yr 



Major method 



Mining 



Beneficiation 



Tungsten 
product 



Status 



Australia: 

Kara 180 

King Island 420 

Mount Carbine 1 ,700 

Mount Mulgine 2,000 

Torrington 300 

Austria: Mittersill 400 

Bolivia: 

Bolsa Negra 58 

Chambillaya 92 

Chicote Grande 1 80 

Chojlla 280 

Enramada 185 

Kami 114 

Pueblo Viejo 36 

Tasna 115 

Viloco 3 

Brazil: 

Barra Verde 194 

Boca de Lage 1 03 

Brejui 1 90 

Zangarelnas 1 05 

Burma: Mawchi 125 

Canada: 

Cantung 350 

Logtung 2,000 

Mactung 350 

Mount Pleasant 650 

France: 

Montredon 100 

Salau 60 

Mexico: 

Baviacora 30 

Los Verdes 300 

San Alberto 200 

Namibia: 

Brandberg West 105 

Krantzberg 105 

See explanatory notes at end of table. 



Open pit Gravity 

Room and pillar, cut and fill. . . . Gravity flotation . 

Open pit Gravity 

... do Gravity, flotation . 

... do do 

Sublevel stoping Flotation 



Lateral stoping 

Sublevel caving 

...do 

Overhand stoping 

... do 

Combined stoping 

Open stoping 

Open stope-block caving 
Combined stoping 



Room and pillar 

Room and pillar, 

shrinkage stoping. 
Room and pillar, open pit. 
Room and pillar, 

shrinkage stoping. 
Shrinkage stoping 



Room and pillar 

Open pit 

Room and pillar 
Blasthole open stope 



Open 

Underhand stoping 



Open pit. 
...do... 
. . . do . . . 



. . . do 

Sublevel stoping 



Gravity 

Gravity, flotation . 
Gravity 



do 
do 
do 
do 
.do 
do 

do 
do 

do 
do 

do 



Gravity, flotation . 

Flotation 

Gravity, flotation , 
. . .do 



Gravity 

Gravity, flotation . 



Gravity . 
. ..do .. 
Flotation 

Gravity . 
... .do . . 



Natural scheelite P 

Natural and artificial scheelite . . P 

APT P 

APT N 

APT N 

APT P 

APT P 

Ferrotungsten P 

APT P 

APT P 

APT P 

APT P 

APT P 

APT P 

APT P 

Natural scheelite P 

... do P 

... do P 

... do N 

APT P 

Natural scheelite P 

APT N 

Natural scheelite N 

APT N 

APT PP 

Natural scheelite P 

APT P 

APT N 

APT P 

APT PP 

APT PP 



25 



Table 5.— Mine ore capacity, mining and beneficiation methods, product, and status— Continued 



Location and 
deposit 



Average 

capacity. 

10 3 t/yr 



Peru: Pasto Bueno 150 

Portugal. 

Borralha 106 

Panasquiera 520 

South Korea: Sangdong 600 

Spam: 

Barruecopardo 513 

La Paniia 250 

Santa Comba 200 

Sweden Yxsjoberg 150 
Thailand 

Ooi Mok 60 

Doi Ngoem 9 

Khao Soon 150 

Turkey: Uludag 560 

Uganda: Nyamalilo 105 

United Kingdom: Hemerdon 1.900 

United States: 

Adamson 52 

Andrew 181 

Atolia Placers 1 .300 

Emerson 189 

Indian Springs 794 

Nevada Scheehte 40 

Pilot Mountain 350 

Pine Creek 338 

Springer 318 

Strawberry 78 

Thompson Creek 25 

Tungsten Queen 150 

N Nonproducer P Producer 



Major method 



Mining 



Beneficiation 



Tungsten 
product 



Combined underground Gravity 



do 

Longwall. room and pillar 
Combined underground 
methods. 



Gravity 

... do 

Combined methods 



Open pit Gravity 

... do do 

Combined underground . . .do 

methods. 
Cut-fill, sublevel stoping Flotation 



Combined underground 
methods 

Open pit 

Open stope 

Sublevel stoping. open pit 

Open pit 

do 



Gravity 



do 
do 
do 
do 

do 



Sublevel caving 

Surface mining 
Placer 



Flotation 
Gravity 
. . . do . . 



Shrinkage stopes Flotation 

do do 

Square set Gravity . 

Open pit do 

Blasthole stoping Flotation 

Shrinkage stoping do 

Sublevel stoping Gravity . 

Shrinkage stoping do 

Cut-fill do 



Status 



APT 

Ferrotungsten . . 

APT 

Natural scheelite . 

APT 

APT 

APT 

Natural scheelite 

APT 

Ferrotungsten . 

... do 

APT 

Ferrotungsten . . 
APT 

APT 

APT 

APT 

APT . .., 

APT 

APT 

APT 

APT 

APT 

APT . : 

APT 

APT 



P 

PP 

P 

PP 

N 

P 

P 

PP 

P 

N 

P 

PP 

PP 

P 

P 

N 

PP 



P Past producer. 



Producing c . 
7pc- 





Figure 16— Total recoverable resource by status 
and mine type. 



Figure 17. 
type. 



-Total ore capacity by status and mine 



26 



4.5 t per workershift, with a current estimated annual ore 
production of only 30,000 t. 

Large-scale open pit operations, such as Mount Carbine 
in Australia, utilize highly mechanized mining methods 
consisting of high-capacity shovels, front-end loaders, and 
trucks. Except for tungsten recovered as a byproduct, the 
tungsten ore at Mount Carbine is among the lowest grades 
currently being mined from MEC deposits. Nevertheless, 
owing to the high degree of mechanization, productivity at 
Mount Carbine is quite high, approximately 95 t per 
workershift, with an annual ore production of approx- 
imately 1.7 million t. 

Underground 

Most (67 pet) of the recoverable tungsten in MEC 
deposits evaluated is potentially available from the 38 
underground mines and deposits. Room-and-pillar, cut-and- 
fill, shrinkage stoping, block caving, sublevel stoping, and 
combined mining methods are commonly employed. 

Most of the Bolivian tungsten mines are developed on 
steeply dipping, irregular hydrothermal veins that require 
conventional stoping methods, resulting in high recovery. 
These mines range in capacity from 3,400 to 180,000 t of 
ore per year. Tasna is atypical among Bolivian tungsten 
mines in that nearly 50 pet of its ore production is mined 
by small-scale block caving. 

The relatively small European tungsten mines, such as 
Santa Comba, Mittersill, and Yxsjoberg, generally employ 
stoping methods with a productivity ranging from 2 to 11 
t per workershift. Wide vein systems are usually mined by 
sublevel caving or by sublevel stoping. 

The Pine Creek Mine in California is an important pro- 
ducer of tungsten in the United States when operating at 
full capacity. The mine employs blasthole stoping at a 
capacity of 1,300 t of ore per day. 

Mineralization in relatively flat-dipping structures can 
be mined by room-and-pillar methods. The King Island Mine 
in Tasmania, Australia, combines highly mechanized room- 
and-pillar methods with cut-and-fill to produce 
approximately 420,000 t of ore annually. A productivity of 
between 10 and 15 t per workershift is generally 
maintained. 

The Panasquierea Mine in Portugal is the single largest 
producer of tungsten in Western Europe. Production is ap- 
proximately 1,625 t/d. Two mining methods are employed, 
room-and-pillar and longwall. In the early 1970's room-and- 
pillar accounted for 75 pet of production, but in the last 3 
or 4 yr longwall methods have been responsible for 80 pet 
of production. The change in mining methods has resulted 
in decreased dilution and lower capital expenditures for 
equipment. 

Cantung, British Columbia, also employs the room-and- 
pillar method at a capacity of 350,000 t/yr of ore. The pro- 
posed Mactung Mine on the Yukon-Northwest Territories 
border has plans to use room-and-pillar techniques also, 
with an annual capacity of 350,00 t of ore. 

The molybdenum deposit at Climax, CO, is mined 
employing block caving at a design capacity of about 44,000 
t/d. When operating at full capacity, the Climax Mine is 
the second largest producer of tungsten (as a byproduct of 
molybdenum) in the United States, and seventh largest 
among MEC producers. 



Solution 

Although it was not evaluated in this study, one of the 
largest known tungsten resources in the United States is 
the Searles Lake evaporite and brine deposit in southern 
California. The deposit contains approximately 77,000 t of 
W0 3 , much of which could be recovered as a byproduct of 
soda ash production. Kerr McGee is currently owner- 
operator of several plants that recover soda ash, salt cake, 
borax, and potash from Searles Lake brines. The Bureau, 
in conjunction with Kerr McGee, has undertaken studies 
to test the technical and economic feasibility of recovering 
byproduct tungsten from these brines (41 ). Bench-scale pilot 
plant studies have shown favorable technical and economic 
potential for a commercial tungsten recovery plant at the 
Westend facility. Approximately 75 pet of the tungsten con- 
tained in brines treated by the Westend pilot plant is poten- 
tially recoverable. The process under evaulation employs 
ion-exchange as the primary concentration method followed 
by chemical precipitation of a tungsten product. 



BENEFICIATION OF TUNGSTEN ORES 

The brittle nature and high specific gravity of tungsten 
minerals (especially scheelite and wolframite) require 
careful processing in order to maintain acceptable 
recoveries. Nearly all tungsten ores require gravity methods 
to produce a concentrate, although some scheelite ores can 
be floated efficiently. The iron content of some tungsten ores 
allows for their upgrading by magnetic methods. 

Most tungsten ores are sized in crushers and grinders. 
These processes require careful monitoring because the 
brittle nature of tungsten minerals can result in problems 
in treatment and recovery. If crushing and grinding are not 
closely monitored, the ore minerals will become finer 
grained than the gangue minerals and will accumulate with 
the finer nontungsten material, making separation more 
difficult. In general, the finer grained the ore minerals the 
more costly recovery is, owing to the necessity for additional 
recovery circuits. 

Some mines employ handsorting prior to milling as a 
means of upgrading the ore. Doi Ngoem in Thailand and 
some of the Bolivian operations utilize this method. Hand- 
sorting at Doi Ngoem reduces the volume of total W0 3 by 
about 10 pet but, at the same time, upgrades ore from a feed 
grade of about 1.60 pet to over 25 pet W0 3 , thus reducing 
overall beneficiation costs. At the Xihuashan Mine in 
China, approximately 100 people are employed to handsort 
3,000 t of ore per day. 

The Mount Carbine Mine in Australia employs a highly 
advanced photometric separation method, which is essen- 
tially an automated "handsorting" method. After crushing 
and grinding, but prior to gravity treatment, the ore is mov- 
ed by belt and scanned by a light beam that is reflected by 
the ore. The reflected light is analyzed by a computer, which 
identifies the more reflective ore-bearing quartz from bar- 
ren schist. Acceptable ore is blown off the belt by computer 
controlled airjets onto another belt that transports the 
upgraded ore to secondary and tertiary crushing before it 
is sent to the gravity plant, where wolframite and scheelite 
concentrates are produced. Figure 18 illustrates the flow 
of material at the mill plant. 



27 



Opencut 
mine 




Loader 



Truck 



Primary 
crusher 



>\ Screen 
1 tower 



Fines 



Wet 

screen 

tower 



Dewatering 



Screens 



Jigs and spiral 
concentrators 



Concentrates 



To tailings 
dam 




A-frame 
Graded ore 
stockpile 



Secondary 
crushing 



Tertiary 
crushing 



Beneficiation 

with jigs and 

shaking tables 




J?.VV Product 
0\o'5>oC\ stockpile 



)° :, Waste 
°.b b'°" stock P |le 



ABWft'f&KSl 



Haulage 



Waste dump 



I I 






Concentrate 
recirculated 



Tailings 




Rod grinding mill 



Jigs and spiral 
concentrators 



Crude 
concentrates 



Concentrate cleaning section 

Rotation tables 

Dry magnetic separation 

Shaking tables 
High tension separation 



Wolframite 

I 



Scheelite 



To tailings dam -*■ 



I 



nl Drummed concentrates 
U U dispatched overseas 



Figure 18.— Flowsheet. Mount Carbine operation. 



After crushing and grinding 'and handsorting at some 
mines i, nearly all tungsten ores are separated by gravity 
techniques using jigs, cyclones, and or tables. Concentrate 
grades of 70 pet are often produced using gravity methods. 
For commercial reason.-, standard grade scheelite concen- 
trates are expected to assay more than 70 pet WO,. 



wolframite 60 pet. Producers employing gravity separation 
techniques include all evaluated Bolivian, Australian, and 
Brazilian opi u 

Additional treatment of gravity concentrates is 

times practiced as an upgrading process. Magnetic 

separation isol edton move ilmenite, magnetite, and 



28 



other minerals. At Uludag, Turkey, approximately 70 pet 
(by weight) of the feed is rejected by dry magnetic separa- 
tion. If sulfides are present in the gravity concentrates, flota- 
tion or roasting is often used to upgrade the concentrate. 
This is of particular importance in the case of wolframite 
mineralization, which is often associated with sulfide and 
arsenide minerals. 

Some scheelite ores can be effectively concentrated 
using flotation. Flotation recoveries can reach about 80 pet 
and generally produce a tungsten concentrate of between 
65 and 70 pet W0 3 . 

Sangdong (Republic of Korea) and Mittersill (Austria) 
are probably the most vertically integrated tungsten opera- 
tions in the world. The operations produce artificial 
scheelite, APT, high-grade natural scheelite, tungsten 
metal, tungsten oxide, and carbide powder. Sangdong also 
produces byproduct bismuth and molybdenum. Sangdong's 
postmill processing plants have high capacities and the flex- 
ibility to respond to changing market demands by varying 
their product output. Figure 19 is a simplified flowchart of 
Sangdong's concentration method. Mined ore is ground, 
classified, and floated. Flotation separates the sulfide 
minerals, resulting in the production of a bismuth- 
molybdenum concentrate from the scheelite minerals that 
are contained in the tails. The tails pass to flotation cells, 
from which a low-grade tungsten concentrate (10 pet W0 3 ) 
is recovered. The 10-pct concentrate is upgraded by grav- 
ity concentration to a 65-pct W0 3 concentrate and an 8-pct 
W0 3 tailing. The 65-pct concentrate is leached with acid 
to remove apatite and other impurities. The final concen- 



Feed 




Tails 



Bi-Mo 
concentrate 



Promoter 
Fuel oil 
Oleic acid 
Sodium silicate 
Soda ash 



Scheelite 
rougher 
flotation 



Concentrate 



Final 
tailings 



Concentrate 



Acid 
leach 



Wet table 

gravity 

concentration 



Natural 
scheelite 



Tails 



Chemical 
plant 



APT 



Figure 19. — Flowsheet, Sangdong concentration process. 



trate assays 72 pet W0 3 . The 8-pct W0 3 tailings are 
reground and tabled. This upgraded material is then con- 
verted to artificial scheelite. Some of the artificial scheelite 
is converted to APT, the amount depending upon market 
needs. 

As mentioned previously, some operations produce 
tungsten concentrates that require additional treatment 
before they can be processed to APT or ferrotungsten. This 
is practiced to reduce consumption of chemicals and energy 
requirements. Major upgrading processes are flotation to 
remove base metal, arsenic, and molybdenum sulfides; 
magnetic separation to remove wolframite and garnet; elec- 
trostatic separation to remove cassiterite; roasting to 
eliminate arsenic, sulfur, flotation oils, and organics; 
grinding to ensure higher solubility; and acid leaching to 
remove carbonates. 



POSTMILL PROCESSING 

Tungsten concentrates can be converted to a variety of 
tungsten products. Products are determined primarily by 
the chemical composition of the concentrate, but marketing, 
geographical, and political factors also play a role. In this 
study, APT, artificial scheelite, natural scheelite concen- 
trate, and ferrotungsten were considered as marketable 
tungsten products. Operations that produce wolframite con- 
centrates (e.g., several Bolivian mines) were assumed to 
have their concentrates transported to Europe to be con- 
verted to APT. 

Ammonium Paratungstate (APT) 

Concentrate is the primary tungsten unit in the 
tungsten industry and APT is the largest consumer of con- 
centrate. APT is an intermediate product, in powder form, 
for virtually all major tungsten products (fig. 1). Although 
there are several methods to produce APT, the most wide- 
ly employed method is comprised of the following four main 
stages (fig. 20): 

1. Autoclave digestion of the concentrate with soda ash 
to dissolve the tungsten minerals. 

2. Removal of impurities from the sodium tungstate 
solution (primarily molybdenum and silica). 

3. Organic solvent extraction to concentrate and purify 
the sodium tungstate solution and convert it to an am- 
monium salt solution (APT). 

4. Crystallization and drying of the APT from the am- 
monium solution. 

Feed to most APT plants is in the form of scheelite and 
wolframite containing approximately 65 pet W0 3 , plus im- 
purities including arsenic, molybdenum, and sulfur. In some 
cases, the concentrates are roasted to decrease the sulfur 
and arsenic content or preleached with acid to remove 
carbonates. 

The purpose of the first stage is to convert tungsten con- 
centrate into sodium tungstate by pressure leaching with 
soda ash. The resulting slurry is cooled and filtered. The 
insoluble portions are recovered and discharged to waste. 
Approximately 98 pet of the tungsten and molybdenum are 
dissolved in the pressure leaching step. 

The second stage consists of the removal of the principal 
impurities from the sodium tungstate solution, primarily 
molybdenum and silica. 

In the third stage, a circuit removes any remaining im- 
purities not removed in the previous stage and also contains 



29 



Scheelite concentrate 

(or blend of W0 3 concentrates) 

(65 pet W0 3 ) 



Scheelite concentrate teed 
(7-15 pet W0 3 ) 





Digester 




■ 


i 






Removal of 
impurties 












' 


i 


Molybdenum 
recovery 




Organic 
phase 




I 




i 


i 


Molybdenum 


Crystallizer 



Dissolution of 
tungsten minerals 



Purification by 
solid waste 
removal, precipitation 
of contaminant 



Organic extraction 
process and 
conversion to APT 



Precipitation of APT 
solution crystals 





{ 




Autoclave 




Residual 


' r 


tungsten 


Impurities 

removal 








■ 






Recovery of 

residual 

tungsten 

and 

molybdenum 

solids 




1 




Precipitation 










\ 












■ 


Molybdenum 


Dryer 
Pelleti?er 
Packaging 



Autoclave 
digestion to 
produce sodium 
tungstate solution 



Removal of 
impurities 
(principally silica 
and molybdenum) 



Precipitation of 
tungstate 



Drying and 
packaging of 
artificial scheelite 



APT 

Figure 20. — Flowsheet, ammonium paratungstate production 

process. 



Artificial scheelite 
(CaWO«) 

Figure 21 .—Flowsheet, artificial scheelite production process. 



circuits to convert the sodium tungstate solution to am- 
monium tungstate. 

The fourth stage is the preparation of the final dried 
product from solution. This is accomplished by producing 
an oversaturated solution causing precipitation of APT 
crystals. The crystals are dried, ground, and packaged. 
Assays are usually between 89 and 90 pet W0 3 , and con- 
tain minor impurities 'table 6). 



Table 6.— Chemical composition of APT 



Assay 



Elements, ppm: 
AJ 
Ca 
Fe 
Mo 
Na 

Compounds, pel 

NHj 

W0 3 
Ignrtion loss 
Moisture 





5 




10 




20 




25 




20 




15 




5.4 




'89 


pel 


11 


pet 


0.5 



•70 5 pet W 



Artificial Scheelite 

Artificial or synthetic scheelite (CaWOj is produced 
from low-grade concentrate- 7 I 20 pet \VO,i. usually at 
the minesite. The processing yields a high-grade tungsten 
concentrate free of impurities (especially molybdenum). The 
production of artificial scheelite is an alternative method 



to selective flotation, which produces a high-grade scheelite 
concentrate. The most significant producers of artificial 
scheelite in the MEC's are Sangdong in the Republic of 
Korea, and King Island in Australia. 

Synthetic or artificial scheelite is used primarily as a 
direct additive to molten steel for tungsten alloys. The proc- 
ess for production of artificial scheelite (fig. 21) consists of 
the following four major stages: 

1. Autoclave digestion with soda ash to produce sodium 
tungstate. 

2. Removal of impurities. 

3. Precipitation of the tungsten or calcium tungstate 
and packaging. 

4. Recovery of residual tungsten from impurities. 
Stage 1 consists of the digestion of scheelite concentrate 

with soda ash. The process produces soluble sodium 
tungstate and leaves impurities as solids. The solutions and 
solids are separated by filtration, and the solids arc 
to a disposal site. 

Stage 2 is designed to precipitate any impurities that 
remain in the sodium tungstate solution, primarily silica 
and molybdenum. The molybdenum compounds are ti 1 
to recover residual tungsten in stage 4. 

In stage 3, the sodium tungstate is healed and ch 
ically treated in order to cause precipitation ol 
tungstate. The resulting precipitate is w 
pelletized. The pellets are 1 

In stage 4, any residual tungsti 
returned to stage 1. Overall, tungsten r< 
imately 98 pet. Typical as 
scheelite are listed in table 7. 



30 



Table 7.— Chemical composition of natural and artificial 
scheelite, percent 



Natural Artificial 

As ."' 0.01 0.01 

B\ .'.'.'.'.'. • 01 01 

CaO 22.14 22.25 

Cu Trace Trace 

Fe ' 1 00 30 

Mn 03 Trace 

Mo ". '.'. 1 00 02 

p .01 03 

Pb Trace Trace 

S ...... 03 .30 

g D Trace Trace 

Si0 2 .'.'.'.'.'.'.'.'.'.'.'.'.'. 2.68 .40 

Sn Trace Trace 

W0 3 730 ° • 75 00 

Zn 02 .01 



Scheelite Concentrate 

Some mining operations, such as Cantung in Canada, 
King Island in Australia, and Sangdong in the Republic of 
Korea, primarily produce natural scheelite concentrate, 
which requires little, if any, special beneficiation steps. 
Natural scheelite contains variable amounts of 
molybdenum because of the close geochemical relationship 
between scheelite and powellite mineralization. Natural 
scheelite concentrates are suitable as direct feed to the tool 
steel industry where molybdenum is desirable. 

Natural scheelite concentrates are produced in quantity 
at Sangdong. In 1983, the mine was the largest and most 
important MEC producer of natural scheelite. These con- 
centrates, typical of most scheelite concentrates, contain up 
to 1.7 pet Mo, 3.80 pet Si0 2 , less than 0.01 pet As, plus other 
minor constituents (table 8). In comparison, artificial 
scheelite contains up to 0.02 pet Mo, less than 0.70 pet Si0 2 , 
and less than 0.01 pet As. 



Wolframite or ferberite 
concentrate feed 



Crushing 



'Ferrotungsten 

slag 
(50-55 pctW) 



Waste 
slag 



Roasting 



Preparation 
for arc 
furnace 



Primary arc 
furnace 



Cooling 
crushing 



Secondary 
arc furnace 



Reduction (when 
As and S 2 present) 



Drying, briquetting, 
crushing 



80 pet 

ferrotungsten 

packing 



Preparation of slag 
(15-25 pet W) for 
secondary arc furnace 



Smelting of slag 



High-grade 
ferrotungsten 

Figure 22.— Flowsheet, ferrotungsten production process. 



Table 8.— Chemical composition of ferrotungsten, percent 

Assay 

As '0.10 

C .60 

Cu .10 

Mn .75 

P .06 

S .06 

Sb '.08 

Si 1.00 

Sn '.10 

W0 3 288-99 

'Sum of As, Sb, and Sn not to exceed 0.2 pet. 
2 70 to 80 pet W. 



Ferrotungsten 

Ferrotungsten is produced from tungsten concentrates 
by various methods. The most commonly used is the elec- 
tric carbon arc reduction process (fig. 22). Ferrotungsten is 
produced from clean ferberite concentrates or from a 
scheelite and wolframite admixture. The concentrates 
should be low in manganese. Table 8 shows the composi- 



tion of a typical ferrotungsten concentrate. If sulfides or 
arsenides are present in the concentrate, prior roasting may 
be required. 

The electric arc reduction process consists of two 
stages— reduction of concentrates and secondary arc reduc- 
tion. In the first stage, the concentrate is briquetted with 
carbon, lime, and fluorspar, and smelted along with recycled 
low-grade slag from the secondary arc furnace. Lime and 
fluorspar are added to flux the silica and other impurities. 
The first or primary stage smelting results in a product 
assaying 15 to 25 pet W, which is further processed in the 
second stage furnace, resulting in a high-grade fer- 
rotungsten product assaying 80 pet W, which is sized and 
packaged. The slag from the secondary furnace is crushed, 
ground, and dried, followed by briquetting with charcoal 
and recovered dust. Silica, lime, fluorspar, and bauxite are 
once again added as fluxes. The mixture is heated to 2,000° 
C and the resulting metal, assaying 50 to 55 pet W, is fed 
to the primary stage furnace. The overall recovery of 
tungsten from concentrates ranges from 97.5 to 99 pet. The 
losses usually occur from dust, fumes, and handling. 



31 



OPERATING AND CAPITAL COSTS 



Operating and capital investments for the apropriate 
mining, beneficial ion. and postmil] processing methods 
were estimated for each property. Where possible, actual 
mining capital and operating costs were gathered from 
published material or contacts with company personnel 
When actual costs were unavailable, costs were either 
estimated using standardized costing techniques or derived 
from the Bureaus capital and operating cost manual using 
the cost estimating system CES i2). 



OPERATING COSTS 

Operating costs for the mine and mill include materials 
utilities, labor, administrative costs, facilities maintenance 
and supplies, and research. The operating costs presented 
in this section are weighted averages based on a per-metric- 
ton-of-ore basis and per pound of W0 3 in the tungsten pro- 
duct i APT. ferrotungsten. artificial scheelite, and scheelite 
concentrate' over the life of the operation. 

Operating costs were analyzed on the basis of mine type 
'surface, underground i. and on an individual and/or 
aggregated country basis. 

Surface and Underground 

At the time of this analysis, 8 surface and 30 
underground mines were considered to be producers and 
11 surface and 8 underground properties were non- 
producers. Figure 23 shows weighted average operating 
costs for producers and nonproducers. presented in terms 
of dollars per metric ton of ore and dollars per pound of 
recovered \\ 3 in product. Within each category, the costs 
are further broken down into three components: mine mill 
and postmill processing 'which includes transportation to' 
the location of processing to the first marketable product) 

Properties with the lowest operating costs generally 
utilize efficient mining techniques and modern equipment 
resulting in high productivity levels. The property with the 
lowest mine operating cost per metric ton of ore is the 
Andrew Mme in California, which is a surface operation 
using a front-end loader on easily accessible broken colluvial 
material. Among producing surface operations, the highest 



mine operating cost is at Baviacora, Mexico, where 
primitive hand mining techniques are employed, resulting 
in very low productivity. 

Among underground operations, higher operating costs 
are generally associated with more complex ore bodies 
unstable ground conditions, and complex ores that require 
expensive beneficiation techniques. In the case of Bolivia 
Mexico, and other less developed countries, low productivity 
is an important factor t umbuting to relatively hieh 
operating costs. 

Figure 23 indicates that, as expected, for surface opera- 
tions, nonproducers are more costly than producers 
However, for underground operations, nonproducers are less 
costly, in terms of both dollars per metric ton of ore and 
dollars per pound of W0 3 . The reason for this anomaly is 
that properties evaluated as underground nonproducers in- 
clude large, highly mechanized, relatively low cost opera- 
tions (e.g., Mactung, Mount Pleasant). This cost differen- 
tial is indicated in the mine cost portion of total operating 
costs. For underground nonproducers, the weighted average 
mine cost is $13.90/t ore, compared with $20 20/t for 
underground producers. Also contributing to this cost dif- 
ference is that the figure for underground producers in- 
cludes several relatively high cost operations in the United 
btates, many of which have shut down or severely curtailed 
production since the time of this analysis. The six producing 
U.b. properties are among the highest cost operations 
evaluated. The weighted average mine operating cost for 
these properties is $30.60/t ore (versus $20.20/t for all 
underground producers). 

This cost anomaly (i.e., nonproducers more costly than 
producers) is even more apparent in terms of dollars per 
pound of W0 3 . The total operating cost for underground non- 
producers is 43 pet lower than for producers ($2.45 versus 
$4.30), compared with 12 pet lower cost ($38.35 versus 
*«iL05) in terms of dollars per metric ton of ore. This is due 
to the grade differences among underground properties The 
weighted average feed grade for nonproducers is 0.74 pet 
W0 3 , compared with 0.53 pet for producers. 

It must be noted that the anomalous cost difference be- 
tween nonproducing and producing underground properties 
does not hold true when an economic analysis is performed 
Nonproducers would require large capital investments that 



Surface 



$9 15 



$12 10 




$4 90 



f 1 



Producers 
Nonproducers 

Producers 
Nonproducers 




245 



$5 70 r 
Figure 23-Operat,ng costs, surface versus underground. Dollars 




$4 30 



$38.35 



r^*3,o 5 



KEY 
Mine operating cost 

J J Mill operating cost 

LNX\N| Postmi'l processing cost 

per metric ton of ore (top) and per pound of WO, (bottom). 



32 



must be recovered when the properties begin production, 
while much of the investment for producing mines has 
already been depreciated. The weighted average total pro- 
duction cost for nonproducing underground properties is 
$5.35 at 0-pct DCFROR, compared with $4.30 for producers. 
At a 15-pct DCFROR, the costs are $7.20 and $5.30, 
respectively. 

When comparing costs on a per-metric-ton-ore basis for 
surface versus underground properties, underground prop- 
erties are substantially more costly than their producing 
onproducing counterpart" On a doll8r-per-pcurjd-W0 3 

is, though, both producing and nonproducing 
underground properties are less costly than their surface 
counterparts ($4.30 for underground producers versus $4.90 
for surface producers, $2.45 for underground nonproducers 
versus $5.70 for surface nonproducers). Feed grades again 
account for this anomaly. The weighted average feed grade 
for underground producers averages 0.53 pet W0 3 , com- 
pared with 0.14 pet for surface producers. Likewise, the 
weighted average feed grade for underground nonproducers 
averages 0.74 pet, compared with 0.13 pet for surface non- 
producers. Clearly, the feed grades of properties that do or 
would produce as underground mines are sufficiently high 
to offset the higher operating costs associated with 
underground mining methods. 

Regional Overview 

Figure 24 illustrates operating costs for producing and 
nonproducing tungsten properties aggregated by region or 
country groupings. The costs are presented in three 



Table 9.— Commodity prices used in study 

Price 

Ammonium paratungstate (APT) lb $5.37 

Arsenic trioxide (As 2 3 ) lb .45 

Bismuth lb . . 1 .33 

Copper lb . . .79 

Ferrotungsten lb . . 5.61 

Gold tr oz 480.00 

Lead lb. . .22 

Molybdenum lb . . 3.83 

Scheelite 1 lb 3.63 

Silver tr oz 1 2.40 

Tin lb. . 5.53 

Zinc lb. . .39 

'Artificial and natural. 



segments: mine, mill, and postmill processing. Also shown 
are credits derived from the sale of byproducts. Prices used 
to determine byproduct revenues are shown in table 9. 

Producers 

The seven producing United States properties (one sur- 
face, six underground) have the highest weighted average 
total and mine operating costs of the country groupings 
shown. The mine operating cost for U.S. producers averages 
$3.58/lb W0 3 ($27.19/t ore), compared with $2.35/lb 
($12.16/t) for all producers, and the total operating cost for 
underground U.S. producers is $6.33/lb ($48.33/t), versus 
$4.69/lb ($24.65/t) for all underground producers. The high 
cost of U.S. producers relative to producers as a whole 
results from expensive mining methods that must be 
employed at some U.S. operations. 

The low mine operating cost ($0.99) for the "other" 



Producers 



KEY 
Byproduct credit 

I Mine operating cost 

E".". , . , . , .i 
:■:•:•:•:•! Mill operating cost 

[^\^\| Postmill processing cost 




DOLLARS PER POUND OF W0 3 
Figure 24. — Operating costs, regional basis. 



33 



country grouping is heavily influenced by two properties 
(Sangdong. Republic of Korea, and Canning. Canada) which 
together account for nearly 23 pet of the average annual 
WO s produced at the 3S producing properties. These two 
properties are highly mechanized, efficient operations with 
high grades. The in situ grade is 1.32 pet WO. at Canning. 
0.86 pet at Sangdong. The Si. 54 mine cost for Australia is 
heavily weighted towards King Island, which accounts for 
nearly 50 pet of the annual recoverable W0 3 for the three 
Australian producers evaluated. Although an underground 
operation. King Island has a high grade compared with the 
two producing lian properties (Kara and 

Mount Carbin< King Island's in situ grade averages 1.03 
pet WO . compared with 0.73 pet at Kara and 0.10 pet at 
Mount Carbine. 

Mil] operat sts are comparable for all country 

groupings except Bolivia ($0.80) and "other" ($0.72). Boli- 
vian milling operations enjoy the advantage of low labor 
and high feed grades. The in situ grade for Bolivian 
- ts averages 0.71 pet W0 3 . considerably higher than 
for all but Thailand and the Republic of Korea (Sangdong 
only. As is the case with mining costs, the relatively low 
mill operating cost for the "other" group is affected by Can- 
tung and Sangdo; 

Postmill processing cost includes the cost of processing 
low-grade tungsten concentrate to the first marketable prod- 
uct 'artificial scheelite or APT), the cost of processing 
byproducts to a marketable form, and transportation to the 
point of sale. This cost can thus vary widely among the prop- 
erties evaluated. The weighted average cost in this category- 
is approximately $1.00 for all producers. Among the coun- 

-roupings shown in figure 24. Bolivia has the highest 
postmill cost 'SI. 46) since most production from that coun- 
try was assumed to be converted to APT in Europe; 
transportation is a significant portion of the cost. The low 
postmill processing cost for Peru and Brazil is largely af- 
fected by the low cost of Brazilian properties, which pro- 
duce natural scheelite. In fact, nearly all of the postmill 
operating cost for this group is attributable to Pasto Bueno. 
Peru, which produces copper, lead, zinc, and silver as 
byproducts. These byproducts, however, account for the 
$0.29 credit for this group of properties. 

Nonproducers 

Among nonproducers, the five U.S. properties have the 
highest cost in all categories, resulting in a substantially 
higher total operating cost than for all other country group- 
ings. Mine operating cost for U.S. nonproducers averages 
$2.79, compared with an average of $1.63 for all non- 
producers; the average total operating cost for U.S. non- 
producers is $7.6' $3.91 for all nonproducers. This 
is in part a consequence of the fact that the selection pro- 
cess of properties for this study resulted in inclusion of a 
relatively large number of deposits in the United States, 
for which resource data are more readily available than for 
nonproducing deposits in foreign countries. Adequate 
resource data are generally available only for foreign 
dep*. are likely to be developed in the forseeable 
future owing to their favorable cost position relative to 
producers. 

In this instance, the high cost of U.S. nonprodua 
compared with all nonproducers is not attributable to grade. 
In fact, the a ■ pet WO, for U.S. nonproducers 

|ual to the average for all nonproducers evaluated On- 
reason for the comparatively high cost of 1 S. nonproducers 
is the difference in capacity bet 3 nonproducci 



other nonproducers. The average capacity for U.S. non- 
producers is 670 t yr WO .„ versus 863 for all nonproducers. 
More importantly, U.S. properties would be mined using 
relatively expensive methods dictated by the characteristics 
oi' the ore bodies, which are similar to those at producing 
U.S. operations that experience high operating costs. As 
discussed earlier, relatively high labor rates in the United 
States represent a substantial portion of the operating cost 
of U.S. operations. 

The relatively large byproduct credit for African non- 
producers is attributable to the potential recovery of signifi- 
canl amounts of tin from the Brandberg West property. The 
postmill processing cost for the three properties in this group 
is correspondingly high in comparison with other groups, 
but the net operating cost (mine plus mill plus postmill proc- 
essing minus byproduct credits) compares favorably with 
that for other country groupings. The net operating cost for 
Africa is $3.99. lb W0 3 , compared with an average of $3.54 
for all nonproducers. 

Producers Versus Nonproducers 

The weighted average total operating cost for non- 
producers is lower than that for producers ($3.91 versus 
$4.69, not including byproduct credits). This primarily 
results from the low mine cost for nonproducers, which, as 
stated earlier, is largely influenced by a few large, low-cost 
properties with relatively high grades. The most important 
of these is Mactung, Canada, with an average in situ grade 
of 0.96 pet W0 3 , and a high-grade portion containing 15 
million t grading 1.37 pet. As stated earlier, however, this 
apparent discrepancy disappears when an economic analysis 
is performed, since nonproducers would require large capital 
investments that must be recovered when production 
begins. 



POSTMILL TRANSPORTATION AND PROCESSING 

The transformation of tungsten concentrates available 
to the MEC's into the intermediate products of APT and 
ferrotungsten is practiced primarily in the industrialized 
countries of Japan, Republic of Korea, Austria, the United 
States, and Western Europe. 

There are several countries that produce significant 
amounts of APT from concentrates for the western market. 
They include Austria, Japan, China, Republic of Korea, the 
United Kingdom, and the United States. Much of the con- 
centrate treated originates in other countries. 

To the United States, the most important exporters of 
APT are France, China, Republic of Korea, Sweden, and 
the Federal Republic of Germany. The major U.S. producers 
are Union Carbide in Pine Creek, CA; AMAX at Ft. 
Madison, IA; Sylvania at Towanda, PA; and General Elec- 
tric in Cleveland, OH. 

None of the producing mines evaluated in this study pro- 
duce artificial scheelite as a primary product. In every case, 
artificial scheelite is produced at or near the minesite. The 
two largest art ificial scheelite producers are at King Island, 
Australia, and Sangdong in the Republic of Korea. 

Ferrotungsten is produced in tnosl industrialized coun- 
tries principally from scheelite and ferberite concentrates. 
Ferrotungsten 's application in alloy makes it an integral 
part of any well developed tool steel industry. Most fer- 
rotungsten producers also manufacture other ferroalloys 
such as ferrovanadium, fei romolybdenum, ferrochromium, 
and ferrotitanium. 



34 



In general, annual plant capacities range between 100 
and 2,500 t of ferrotungsten. Austria, Belgium, Brazil, 
France, Japan, Portugal, the United Kingdom, and the 
Federal Republic of Germany are major ferrotungsten pro- 
ducers. Smaller ferrotungsten producers are India, Luxem- 
bourg, Mexico, Republic of Korea, and Spain. 

Union Carbide has the only large ferrotungsten plant 
in the United States. The plant has an annual capacity of 
about 7 million lb of ferrotungsten. Molycorp has a plant 
in Washington, PA, but its output is very small. The United 
States is currently a net importer of ferrotungsten. 

Transportation 

Table 10 lists the actual or assumed destination and 
product form for producing and nonproducing properties 
evaluated. In most cases, the destination for postmill 
processing and the tungsten product were known. For other 
producing and nonproducing mines, assumptions were 
necessary. In some cases, concentrates might be sent to dif- 
ferent countries owing to year-to-year changes in sales 
contracts. 

For some deposits, final tungsten products were not 
known. When concentrates were low-grade scheelite con- 
taining arsenic, sulfides, or other contaminants, or when 
the concentrates were wolframite, APT was the assumed 
product. Ferrotungsten was assumed in the case of ferberite. 
Clean scheelite concentrate was assumed to be sold free on 
board (f.o.b.) at the mill. 

Table 10 indicates that all domestic concentrates are 
converted within the United States, but the United States 
also treats concentrates from Canada and Mexico. Most of 
Bolivia's tungsten concentrates are shipped to Europe 
although some portion is probably shipped to Japan and the 
United States. Most Bolivian concentrates are shipped from 
Antofagasta, Chile, to Europe for processing. 

Transportation costs for concentrates requiring further 
treatment, whether to APT or ferrotungsten, are generally 
very similar. Grade apparently does not play a major role 
in determining shipping rates. International transportation 
costs for shipping tungsten concentrates to major destina- 
tions were estimated using available concentrate shipping 
schedules for ocean transport. The costs include all charges 
from receipt on the shipping pier from a land carrier to 
loading on a land carrier at the destination ocean port. The 
estimated shipping costs listed in table 11 do not include 
custom duties or custom broker charges. Land transporta- 
tion, specifically rail and/or truck, were estimated on a 
deposit-by-deposit basis. 

Processing Costs 

The operating costs for processing tungsten concentrates 
depend on a large number of factors, including desired 
product, concentrate grade, mineralogy and contaminants, 
reagent costs, power and labor costs, and the age of the plant 
and its capacity. The following discussion presents the costs 
for production of APT, ferrotungsten, and artificial scheelite 
(in January 1981 dollars). A U.S. location and U.S. labor 
rates were assumed. All direct and indirect costs for labor, 
electricity, fuels, chemicals, and parts are included. Land 
acquisition, finance costs, legal expenses, depreciation, and 
custom toll charges were not included. 

Ammonium Paratungstate (APT) 

The operating cost estimates in table 12 represent a 



Table 10.— Actual or assumed destinations for tungsten 
concentrate 



Location and deposit 



Status 



Primary tungsten 
product 



Point of sale 



Australia: 

Kara 

King Island 

Mount Carbine . . 

Mount Mulgine . . 

Torrington 

Austria: Mittersill 
Bolivia: 

Bolsa Negra 

Chambillaya 

Chicote Grande . 

Chojlla 

Enramada 

Kami 

Pueblo Viejo . . 

Tasna 

Viloco 

Brazil: 

Barra Verde .... 

Boca de Lage . . 

Berujui 

Zangarelhas .... 

Burma: Mawchi 

Canada: 

Cantung 

Logtung 

MacTung 

Mount Pleasant . 
France: 

Montredon 

Salau 

Mexico: 

Baviacora 

Los Verdes .... 

San Alberto 
Namibia: 

Brandberg West 

Krantzberg 

Peru: Pasto Bueno . . 
Portugal: 

Borralha 

Panasquiera. . . 
Republic of Korea: 

Sangdong. 
Spain: 

Barruecopardo . . 

La Parilla 

Santa Comba. . . 
Sweden: Yxsjoberg . 
Thailand: 

Doi Mok 

Doi Ngoem 

Khao Soon 

Turkey: Uludag 

Uganda: Nyamalilo . . 
United Kingdom: 

Hemerdon. 
United States: 

Adamson 

Andrew 

Atolia Placers . . 

Emerson 

Gunmetal 

Indian Springs . 

Nevada 

Scheelite 

Pine Creek 

Springer 

Strawberry 

Thompson Creek 

Tungsten Queen 



Producer 

. . do 

...do 

Nonproducer . 

...do 

Producer 



.do 

.do 
.do 
.do 
.do 
.do 
.do 
.do 
do 



Scheelite f.o.b. 

. . .do f.o.b. 

APT Japan. 

APT Japan, Europe. 

APT Do. 

APT f.o.b. 

APT Europe. 



Ferrotungsten 

APT 

APT 

APT 

APT 

APT 

APT 

APT 



Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 



.do 

.do 

do 

Nonproducer . 
Producer 

. . . do 



Nonproducer . 

...do 

...do 



... do 
Producer . 



...do 

Nonproducer . 
Producer 



Nonproducer. 

. . . do 

Producer 



..do 
do 
.do 



Scheelite f.o.b. 

. . .do f.o.b. 

. . do f.o.b. 

. . .do f.o.b. 

APT Japan, Europe. 

Scheelite United States, 

Canada. 

APT Do. 

Scheelite Do. 

APT Europe. 

APT Do. 

Scheelite f.o.b. 

APT United States. 

APT Do. 

APT Do. 

APT Europe. 

APT Do. 

APT • Europe, Japan. 



Ferrotungsten 

APT 

Scheelite .... 



Europe. 
Do. 
Do. 



do 
do 
do 
do 



Nonproducer . 
Producer 
Nonproducer. 
Producer 
Nonproducer 
.do 



Producer 

. . . do 

Nonproducer. 
Producer 
Nonproducer 
... do 



APT Do. 

APT Do. 

APT Do. 

Scheelite f.o.b. 

APT Japan, Europe. 

Ferrotungsten . . Do. 

... do Do. 

APT Europe. 

Ferrotungsten . . Do. 

APT Do. 



APT United States. 



Producer 

. . . do 

..do 

. . do 

Nonproducer . 
... do 



APT 
APT 
APT 
APT 
APT 

APT 

APT 
APT 
APT 
APT 
APT 



Do. 
Do. 
Do. 
Do. 
Do. 

Do. 
Do. 
Do. 
Do. 
Do. 
Do. 



35 



Table 11.— Port handling and transportation costs for 

selected major tungsten concentrate trade routes. January 

1981 dollars per metric ton of concentrate 



From — 



To- 



Cost 



Melbourne. Australia 

Canada 

Ba->ot<c«. riia.!<ini: 



Pusan. Republic of 
Koiea 

Arguipa Pe- 
Antofagasta. Chile 



Amsterdam-Rotterdam. Netherlands. 
jelphia-New Jersey. United States 

- mtenJarn-RotterdsiTi Netherla 

ToKyc. Japan 

Amsterdam-Rone'Odir Netheriam IS 
Philadelphia-New Jersey, Uniied States 

Japan 
Amsterdam-Rotterdam. Netherlands 
Philadelphia. United States 
Amsterdam-Rotterdam. Netherlands 
Amsterdam. Netherlands 



$185 
180 
175 
250 
250 

75 
1 80 
170 

35 
-i 55 
150 
250 
250 



Table 12— Estimated operating costs for a 2-mil!ion-lb/yr 
APT plant. Januai-/ 1981 dollars 



Annual 
cost'' 



Labc- S700 

Chemicals and reagents 400 

Power and fuel oil 300 

Operating and maintenance supplies 200 

Miscellaneous services 100 



Cost per 

pound of 

W0 3 in APT 



Percent 

of 

total 



$0 35 


37 


.20 


21 


.15 


16 


10 


11 


.05 


5 



Total 
^direct 



Grand total 



1.700 
200 

1.900 



85 

10 

.95 



2 89 

11 



100 



'In thousand dollars 

J Data do not add to total shown owing to independent rounding. 



2-millinn-lb yr APT plant within a vertically integrated 
company located in the United States. The APT product con- 
tains 89 to 90 pet \V0 3 and the feed is a 65-pct WO, scheelite 
concentrate. All costs are in January 1981 dollars. 

The treatment cost for conversion of a 40-pet-W'O, 
centrate is about Si. 05 lb of WO in APT and a 15-pct-VVO, 
concentrate costs about $1.40. The increase in cost is 
generally related to higher reagent consumption. Concen- 
trate treated on a toll basis may be subject to an additional 
charge of approximately 35 pet to recapture capital invest- 
ment for the processor. 

Ferrotungsten 

The figures in table 13 represent an estimation of 
operating costs (January 1981 dollars) for a l,0i»' 
rotungsten plant located in the United States. The plant 
produces an 80-pct-\V ferrotungsten product using an elec- 
tric arc furnace reduction process to treat a 65-pct-WO, 
concentrate. 

Direct operating costs comprise 89 pet of the total 
ope 1 "' 1 gle expense is for power and 

fuel oil. 95 pet of which is electricity consumed bv carbon 
arc smelters-approximately 7 h:Z()() I 

metric ton of ferrotungsten 

prise 33 pet of the total operating cost. Concentrates proc 
essed to ferrotungsten are generally high grade and 
reIat in. If the concentrate is custom tolled, an ad- 

ditional charge of approximate 

Artifui; af- 

ter the other processing m 



Table 13.— Estimated operating costs for a 1,000-t/yr 
ferrotungsten plant, January 1981 dollars 



Direct 

Raw matetials 

Maintenance materials 
Operating supplies 
Pi wet and fuel oil 
Supervision 
Labors . 
Fringe benefits . 

Total 
Indirect 

Grand total 



Annual 
cost' 



S200 
50 
50 
450 
50 
300 
1 00 



200 
150 



Cost per 

pound of 

W2 

$n 13 
.03 
.03 
.26 
03 
.17 
.06 

".68 

00 



1,350 



Percent 

of 

total 

15 

4 

H 

33 

4 

22 

7 

89 

11 

100 



'In thousand dollars. 

2 ln ferrotungsten. 

3 0perating and maintenance 

J Data do not add to total shown owing to independent rounding. 

production of artificial scheelite are primarily affected by 
labor, power costs, reagent requirements, and plant design 
capacity. Production costs for an artificial scheelite plant 
are not subject to the same constraints as most APT or fer- 
rotungsten plants, for which tungsten concentrates are pur- 
chased on the open market and their products sold com- 
petitively. For those operations, the margin between con- 
centrate costs and end-product prices is very critical to 
profitability. 

Artificial scheelite production from concentrates usually 
takes place in a vertically integrated operation in which 
other concentrates and intermediate products are also pro- 
duced. The production of artificial scheelite does not usually 
account for a significant portion of the total operating cost 
in the overall operation and generally recovers tungsten 
from a concentrate that would otherwise be difficult to 
market. 

Table 14 presents estimated operating costs (January 
1981 dollars! for an artificial scheelite plant with a 
1-million-lb/yr (W0 3 ) capacity. The treated concentrate 

Id range between 7 and 20 pet WO3. 

The greatest portion of the operating cost is in labor (46 
pet 1, followed by power and fuel (15 pet) mostly consumed 
in the autoclaves. Reagents, primarily soda ash and alum, 
comprise 8 pet of the total operating cost. 

Scheelite Concentrate 

Natural scheelite concentrates are produced at most 
major tungsten mines in the world, but not all natural 

Table 14.— Estimated operating costs for a 1-million-lb/yr 
(W0 3 ) artificial scheelite plant, January 1981 dollars 



Direct 
Supervision and labor 
Chemicals and reagents 
Maintenance supplies 
Other operating material 
Power and fuel oil 
Miscellaneous 

Total 
indirect 

Grand total 

'In thousand dollar'. 



Annual 


Cost per 


Percent 


cost' 


pound of 


of 




W0 3 in APT 


total 


$600 


$0 60 


46 


100 


10 


8 


100 


10 


8 


50 


.05 


4 


200 


20 


15 


50 


.05 


4 


1,100 


1 10 


85 


200 


.20 


15 



1,300 



1.30 



100 



36 



scheelite is suitable for immediate use after gravity con- 
centration. As discussed in the "Beneficiation of Tungsten 
Ores" section of this report, scheelite concentrates can be 
upgraded to meet desired specifications by flotation, 
magnetic separation, electrostatic separation, roasting, 
grinding, classification, or acid leaching. The cost for 
upgrading scheelite concentrate to a marketable product 
can be quite variable and is dictated by the individual 
chemical and physical characteristics of the concentrate. 
Most concentrates require several steps while some do not 
require any upgrading at all. The operating costs for 
upgrading a concentrate do not represent a significant por- 
tion of total operating cost; they are usually less than 3 pet. 



CAPITAL COSTS 

Capital costs have been estimated for all deposits 
evaluated in this study. Capital investments include 
expenditures for exploration, acquisition, development, 
mine plant and equipment, constructing and equipping the 
mill plant, and any required infrastructure (e.g., housing, 
roads, water treatment, and power facilities). 

Capital costs for nonproducing deposits reflect the total 
investment required to construct all facilities and begin pro- 
duction. For most of the nonproducers, there have been no 
significant capital investments, although funds may have 
been expended for determination of resources and, in some 
cases, for feasibility studies. Several of the properties (e.g., 
Krantzberg and Brandberg West in Namibia) were pro- 
ducers at one time but have been inactive for a considerable 
length of time. For these properties, the amount of capital 
necessary to reactivate the operations has been estimated. 
Capital costs for producing mines are not presented because 
some of the mines have been producing for many years, ex- 
pansions of different types have occurred at various times, 
and a large portion of initial costs has been depreciated. 

For most deposits, capital expenditures for postmill 
processing are not required because concentrates are treated 
at plants not owned by the mining company, and recovery 
of capital is included in the custom charge. 



Mine and Mill Capital 

The total capital costs, including mine development, 
mine and mill plant and equipment, and infrastructure for 
selected nonproducers are shown on figure 25. Costs are 
presented in terms of both dollars per pound of W0 3 and 
dollars per metric ton of ore capacity. 

As expected, the total capital to develop surface mines 
is substantially lower in terms of dollars per metric ton of 
ore than for underground mines. This is partly due to 
economies of scale differences between surface and 
underground mines. For example, Mount Pleasant and Mac- 
tung were assumed to have annual capacities of 650,000 
and 350,000 t/yr, respectively, compared with 2 million t/yr 
for Logtung and Mount Mulgine. The most important 
reason for the large difference, though, is because it simply 
is more costly to develop an underground mine. The most 
costly mine shown is Mactung, which would require expen- 
sive infrastructure (townsite, water treatment, airport, etc.) 
owing to its remote location. 

In terms of dollars per pound of W0 3 , the cost of develop- 
ing underground properties is generally comparable with 
development of surface properties due to the relatively high 
grade of underground deposits. The relative grades among 
the properties shown can be compared by noting the ratio 
between cost per metric ton of ore and cost per pound of WO ;i 
for a given property, and comparing that ratio with the 
ratios for other properties. In terms of dollars per pound 
of W0 3 , the most expensive mine shown is Mount Mulgine, 
with an in situ grade of 0.27 pet W0 3 , compared with 0.96 
pet at Mactung. Logtung, although a surface operation, 
would be comparatively costly owing to its low grade (0.12 
pet). 

Postmill Capital 

Capital costs for APT, ferrotungsten, and artificial 
scheelite plants have been estimated for the Bureau by 
Davy Mckee Corp. using the following criteria: January 
1981 U.S. dollars, a U.S. location, and U.S. material and 
construction costs. No provisions were made for land ac- 




50 IOO 150 200 

DOLLARS PER ANNUAL POUND DOLLARS PER ANNUAL METRIC TON OF ORE 

OF W0 3 

Figure 25.— Estimated mine capital for selected undeveloped properties. 



250 



37 



Table 15.— Estimated capital costs for a 2-million-lb/yr (W0 3 ) 
APT plant, thousand January 1981 dollars 



Direct 
Process and other equipment 
Plant and other buildings 
•igs disposal system 
Services (power, water, steam, etc ) 
Electrical equipment 
Instrumentation 
Piping 
Miscellaneous 

Total 

Indirect 

eenng services-construction supervision 
Construction 
Insurance, permits, etc 

Total 

Grand totai 



Cosf 

$3,000 

400 

300 

3.100 

1.100 

200 

1.100 

300 

9.500 



1.100 

1,900 

500 

3.500 
13.000 



quisition, loans, legal tees, preliminary eng 
metallurgical studies, and similar costs. 

Ammonium Paratungstate (APT) 

The following capital cost estimate is for an APT plant 
with an annual design capacity of 2 million lb of W0 3 in 
APT 189 to 90 pel \Y< ) (see table 15). The plant would be 
capable of processing 65 pet WO, scheelite or wolframite 
concentrate with acceptable impurity content. 

The total capital cost of the plant on a per-pound- 

capacity lb of APT. or $6.50 lb of contained 

If the plant were to process concentrates grading less 

than 65 pet. or containing contaminants beyond normal 

limits, added process circuitry and costs would be required. 

If the APT plant were built on an existing industrial -in 

part of a chemical complex, a substantial capital sav- 

ould be realized. 

Ferrotungsten 

The following capital cost estimate has been prepared 
for a ferrotungsten plant producing 1.000 t/yr of 80-pct-W- 
content ferrotungsten 'table 16). 

The capital cost on a per-pound basis is approximately 
pet ferrotungsten. or $6.50 lb of W. The capital 
•ould be considerably lower than that shown if the fer- 
rotungsten plant were located within an industrial or 
chemical complex that produced other ferroalloys. Capital 



Table 1 6.— Estimated capital costs for a 1,000-ton/yr 
ferrotungsen plant, thousand January 1981 dollars 

Cost 
Direct: 

Process plant equipment $3,000 

Buildings, utilities and support facilities 1,900 

Electrical equipment 1 ,000 

Instrumentation 400 

Piping, ducting, dust collection, vent systems 1,100 

Miscellaneous (materials handling and storage) 400 

Total 



Indirect: 
Engineering services-construction 

Construction 

Insurance, permits, etc 

Total indirect costs 



7,800 

800 

1 ,800 

400 

3,000 

Grand total . 10,800 



costs can also be lower in a vertically integrated operation 
such as Sangdong, Republic of Korea. 

Artificial Scheelite 

Artificial scheelite is produced from low-grade concen- 
trates, usually at the minesite. Table 17 contains estimated 
capital for a 1-million-lb/yr (W0 3 ) plant. The plant would 
be designed to process 7 to 20 pet W0 3 concentrate and yield 
a low-molybdenum scheelite grading 75 to 78 pet W0 3 . 



Table 17.— Estimated capital costs for a 1-million-lb/yr ar- 
tificial scheelite plant, thousand January 1981 dollars 

Cosf 
Direct: 

Process plant equipment $1 ,800 

Tailings disposal equipment 200 

Other equipment (utilities, facilities, fresh water) 1,200 

Electrical (equipment and materials) 800 

Instrumentation, controls 300 

Piping (process and services) 900 

Miscellaneous 300 

Total 5,500 

Indirect: 

Construction 1 ,200 

Engineering services, field supervision 800 

Insurance, permits, etc 300 

Total 2,300 

Grand total 7,800 



TUNGSTEN AVAILABILITY— MARKET ECONOMY COUNTRIES 



Tungsl i in a wide variety of products, but n 

tung- ided inoneof threi n Con- 

or wolframite. APT. or ferrotung 
All the di I to produi 

the three product* ible product con- 

■ 

•duct forr i ually (o 

likelj ed on thi er ol t he con- 

centrate and mnvl to proe- 

• hree 
products, but rally 

irofitable product form from each dep 
The mi ' indard 



grade concentrate and for other processed forms of tungsten. 

grade concentrates, or concentrates with high levels 

of impurities, generally are subjected to further processing 

and are resold in another form. The trend over the last 

has been toward trade and sales of processed 

intermediate products, such as APT, rather than 

■ hi rate 

The method used in this study for creating a comparable 
homo product was to process these nonstandard con- 

centrates i 'i APT or ferrotungsten, depending on the ore 
miner; lo ["hi method also allowed comparisons between 
pi opeti ies w hose products are not traded on a market, but 
nt her | ii ma vertically integrated company 



38 



to an even more processed form of tungsten (e.g., tungsten 
carbide powder) or are incorporated into another product 
(e.g., tungsten filaments in light bulbs). 

Those properties whose output was evaluated as a con- 
centrate are all scheelite producers. Those properties con- 
taining ferberite as the major ore mineral were evaluated 
as ferrotungsten producers. All of the remaining properties 
were evaluated as APT producers, even though some of 
them market wolframite concentrates of various grades and 
qualities. The costs of converting low grade or otherwise 
poor quality wolframite concentrates into a useable product 
are reflected in the average total cost of production 
estimates for APT properties. 

Generally the product form is determined by the ore 
mineralogy. If scheelite (CaW0 4 ) is the predominant 
mineral, and if the concentrate is relatively pure, then 
scheelite concentrate is the likely product. If wolframite is 
the predominant mineral, any of the three products is possi- 
ble. If it is the iron-rich member of the wolframite series 
(i.e., ferberite, FeW0 4 ), ferrotungsten is a likely product. 
The rest of the wolframite ores, and scheelite that cannot 
be easily beneficiated into a relatively pure concentrate, will 
likely be further processed into APT (or a myriad of other 
tungsten products). 

More than one form of tungsten is produced from some 
operations. For example, Sangdong, Republic of Korea, pro- 
duces all three tungsten product forms plus other tungsten 
products that require additional processing steps. For 
evaluation purposes, properties producing several tungsten 



products were assumed to produce a fixed average amount 
of each tungsten product form (based on past production 
history) in each year of the remaining life of the mine. 

This section is divided into a short discussion of the 
evaluation methodology and an extended discussion of 
tungsten availability. The tungsten availability section is 
further divided into four subsections. Availability of 
tungsten concentrate (scheelite), ammonium paratungstate 
(APT), and ferrotungsten from the mines and deposits 
evaluated in this study are discussed separately. The final 
subsection addresses the availability of tungsten from all 
sources combined. It also includes a general discussion of 
the relationship between the availability results and the 
supply-demand balance in the current tungsten market. 



EVALUATION METHODOLOGY 

An economic evaluation of each mine or deposit provides 
an estimate of the average total production cost for each 
operation over its estimated producing life. The evaluation 
uses discounted-cash-flow rate of return (DCFROR) 
techniques to estimate the constant-dollar long-run price 
at which the tungsten commodity would need to be sold so 
that revenues are sufficient to cover all costs of production, 
including a prespecified rate of return on investment. A 
flowchart of the Minerals Availability Program evaluation 
and analysis procedure is shown in figure 26. 

This section presents the various assumptions used to 



Identification 

and 

selection 

of deposits 



Tonnage 

and 

grade 

determination 



Engineering 

and 

cost 

evaluation 



Mineral 

Industries 

Location 

System 

(MILS) 

data 



MAP 

computer 

data 

base 



Deposit 

report 

preparation 



Taxes, 
royalties, 

cost 
indexes, 
prices, etc. 



MAP 

permanent 

deposit 

files 



Data 
selection 

and 
validation 



Variable 

and 

parameter 

adjustments 



Economic 
analysis 



Data 



Availability 
curves 



Analytical 
reports 



Sensitivity 
analysis 



u 



Data 



Availability 
curves 



Analytical 
reports 



u 



Figure 26. — Minerals Availability Program evaluation procedure. 



39 



evaluate the amount of tungsten potentially available from 
each deposit, and describes the forms in which results are 
presented. An implicit assumption in each evaluation is that 
each deposit represents a separate corporate entity, with 
negative cash flows in the developmental stages carried for 
ward in time as tax losses where allowed), rather than be- 
ing applied against other corporate revenues in the year 
they occur. The life of each property was estimated by 
assuming that the property would operate at 100 pet of mine 
capacity against the demonstrated resource in thai 
property. 

All cap 
the date of tlv S3) arc treated as sunk 

nents incurred less than 15 yr bvU.vc this date 
the undepreciated bal .,- an expenditure 

in January i983 All subsequeni investmi 
reinvestments, operating - ind transportation costs are 
expres onstant January L981 dollars and entered in 

the year they occur in the development plan. Investment 
and operating schedule.- are determined as much as possi- 
ble from published data or plans announced by prop* rty 
owners ! - thai have been explored, but 

where no plans to initiate production have been announced, 
a development plan was assumed The preproduction period 
tor these explored depo-its allows for only the minimum 
id construction time ne< essary to initiate pro- 
duction. Additional time lags and poteni involved 
in filing environmental impact statements, receivini 
quired permits, an nancing. etc.. are not accounted 
for in the anal\> 

All properties that produce other commodities in addi- 
tion in tui gsl edited with revenues from the sale 
of tho.-e byproducts. Additional expenditures required for 



the recovery of those byproducts are charged against the 
operation. 

The relatively low price;- that have prevailed in the 
tungsten market since late 1981 have caused many proper 
including most of the U.S. properties) to spend some 
portion ol 1982 and 1983 temporaril) closed. For purposes 
of this investigation, properties that are temporarily shut 
down hut that ma\ reopen in thi short run are still classified 
a.- producers and assumed to be producing at full capacitj 
after 1983. 

Two separate analyse- were done for this study with 

alternate rate ol I rn on in ified. 

Avei i il cost et production over the hie of each 

property was estimated first with a required DCFROR of 
15 pet. then with a required DCFROR of pet. The 0-pct 
rate is used to evaluate the breakeven point where revenues 
are sufficient to recover total investment and production 
costs over the operation's life but provide no positive rate 
of return. This rate could reflect the investment parameters 
of a project given only market share or developmental con- 
cerns, where potential multiplier effects (e.g., social benefits) 
would offset the lack of company and/or operation-specific 
profitability. For privately owned enterprises or those not 
strictly developmental in natui;e a more reasonable 
economic decisionmaking parameter is represented by the 
15-pct DCFROR. This rate was considered the minimum 
return sufficient to maintain adequate long-term 
profitability and attract new capital to the industry. 

Summary results from the cost evaluations are shown 
in figure 27. Total production costs for properties included 
in the country groupings are broken down into three 
segments: total operating cost, cost at 0-pct DCFROR, and 
cost at 15-pct DCFROR. The product and country groupings 



Scheelite producers 




KEY 

Total operating cost 
0-pct DCFROR 



RS^I 15-pct DCFROR 



xWWWWWWW^ 



— „ 



x\\\\\\\\\^ 



Ex\x\WWWWM 



nzs^^^^^^v^^^ 



I ~~~ 



J 



'0 15 20 

DOLLARS PER POUND OF W0 3 
Figure 27— Total production costs. 



25 



'A, 



40 



correspond with the results as shown in the following sec- 
tions of this report. Availability of each product type is 
discussed in the following sections of this report, along with 
a more extensive discussion of costs as related to 
availability. A few general comments relating to figure 27 
are worth noting here. 

The costs for scheelite producers are low compared with 
corresponding costs for other product types. This is partly 
due to the fact that scheelite from the nine producing 
properties can be sold directly as a concentrate, so that 
postmill processing (as defined in this report) includes on- 
ly transportation. Also, the weighted-average costs for 
scheelite producers are dominated by the two large, efficient 
operations at Sangdong and Cantung. These two properties 
account for 50 pet of the more than 120,000 t of recoverable 
W0 3 in producing scheelite properties evaluated. 

Among the country groupings shown for APT producers, 
the weighted-average costs (all three cost categories) for U.S. 
properties are highest. Reasons for this were discussed in 
the "Operating Cost" section of this report. Note also the 
high 0- and 15-pct costs for APT nonproducers relative to 
corresponding costs for APT producers. The high costs (at 
and 15 pet) for nonproducers reflect the recovery of large 
capital expenditures necessary to develop these properties. 

The costs for ferrotungsten producers cannot be direct- 
ly compared graphically with other costs shown, as fer- 
rotungsten costs are in terms of dollars per pound of W, 
while all others are in terms of dollars per pound of W0 3 . 
By converting ferrotungsten costs to W0 3 equivalents, each 
of the cost segments would be shorter (i.e., costs would be 
lower) by a factor of 0.79. Thus, in terms of W0 3 , the average 
total operating cost for ferrotungsten producers is $5.08 (in- 
stead of $6.43). At pet the cost is $5.77 (instead of $7.31), 
and at 15 pet, the cost is $6.56 (instead of $8.30). 

More detailed results from the cost evaluations of all 
product forms are presented as availability curves in the 
following sections. Total availability curves were con- 
structed by aggregating the results from the individual 
deposit evaluations. The curves constructed for each of the 
three tungsten product forms show total tonnage available 
from each property at the estimated average total produc- 
tion cost value solved for using the DCFROR techniques 
described. Deposit tonnages are ordered on these curves 
from those having the lowest associated average total cost 
to those having the highest. Potential tungsten availabili- 
ty can be seen by comparing an expected long-run constant- 
dollar market price to the estimated average total cost 
values shown on the availability curves. 

Annual availability curves are also constructed and 
presented in the report. These curves show amounts of 
tungsten potentially available each year at various levels 
of average total cost of production. These curves reflect the 
current installed capacity levels at producing deposits, in- 
cluding known expansion and development plans, and 
assumed capacity levels and development schedules at 
undeveloped deposits. 



TUNGSTEN AVAILABILITY 

At the demonstrated resource level, approximately 1.2 
million t of W0 3 is potentially recoverable from 57 primary 
tungsten mines and deposits in MEC's (nearly 146,000 t, 
or 12 pet from the United States). An additional 100,000 
t of W0 3 is potentially recoverable as a byproduct from the 
Climax molybdenum mine in Colorado and 77,000 t from 



the Searles Lake evaporite and brine deposit in California. 
These deposits were not evaluated because byproduct 
tungsten revenues were a small proportion of total 
revenues. Tungsten is recovered at the Climax operation 
but not at Searles Lake. A recovery method for tungsten 
from the Searles Lake brine has recently been developed 
by the Bureau (41), but commercial application has not as 
yet taken place. Tungsten is also available in small quan- 
tities as a byproduct from other mines around the world, 
most notably tin. Some tungsten is recovered from 
molybdenum, copper, gold, and lead-zinc mines, but data 
on actual amounts recovered are generally unavailable. 
Properties with byproduct tungsten were not included in 
the evaluation sections of this study, but are included in 
the discussion of future availability at the end of this 
section. 

Nearly 2.2 million t of W0 3 is contained in 38 mines 
and deposits in the U.S.S.R. and China that were examin- 
ed in the study (and discussed in the "Geology and 
Resources" section). At 70 pet recovery (the average 
recovery rate at MEC operations evaluated was nearly 69 
pet), this translates to 1.5 million t of potentially recoverable 
W0 3 . Total potentially recoverable W0 3 examined is thus 
approximately 1.4 million t (including byproduct tungsten) 
in MEC's only, and 2.9 million t worldwide. 

Average 1980-82 levels of production were nearly 29,800 
t of concentrate (W0 3 content) per year from MEC's and over 
61,000 t/yr worldwide (see figure 3). At these rates of pro- 
duction, demonstrated resources in MEC deposits evaluated 
would last 46 yr. 

For individual deposits and individual countries, the 
ratio of demonstrated resources to current annual produc- 
tion levels varies greatly. For example, China's estimated 
average production from 1980 to 1982 was approximately 
17,225 t/yr of W0 3 , Chinese deposits evaluated for this study 
contain nearly 1.1 million t of recoverable W0 3 (based on 
an assumed 70 pet recovery), giving it about 64 yr of pro- 
duction at a rate of 17,225 of W0 3 per year. The estimate 
for the U.S.S.R.'s production is 11,154 t/yr from 1980 to 
1982. Its recoverable resources are approximately 433,000 
t of W0 3 (assuming a 70-pct recovery), which means it can 
continue to produce at that rate for about 39 yr. Within the 
MEC's, Bolivia (with less than 6 yr of production available 
from demonstrated resources at the average 1980-82 rate) 
and Canada (with more than 120 yr of production at the 
1980-82 rate possible from demonstrated resources) repre- 
sent end points for the ratio of demonstrated resources to 
annual production for deposits evaluated. The availability 
discussions that follow will provide more detailed informa- 
tion about the resources and annual production capacities 
at the deposits in each country. 

Scheelite Concentrate 

This section discusses scheelite concentrates and ex- 
cludes wolframite, even though the largest portion of con- 
centrate traded may be wolframite. Although wolframite 
concentrates are traded widely, they are of varying grades 
and qualities and are generally further processed before 
reaching a final consumer. Scheelite, by contrast, can be 
a direct addition to a steel bath, usually requiring no fur- 
ther processing. All wolframite concentrates (except for the 
ferberite that is processed to ferrotungsten) were assumed 
to be processed to APT in the cost evaluations. 

In this analysis, scheelite processing is assumed to result 
in a nearly homogeneous product from all mines. Natural 



41 



and artificial scheelite arc combined for study purposes even 
though the relative sales price of the two commodities can 
vary by a few percent, depending on market conditions and 
the needs of consumers. The higher purity artificial 
scheelite sometimes commands a premium, but tor the past 
lew years scheelite has been in excess supply and the prices 
have been approximately the same. High-quality natural 
scheelite is produced at some mines, and for some uses the 
generally higher molybdenum content of natural scheelite 
is a desirable characteristic. In general, all scheelite con- 
centrate are traded using a common reference price, with 
the proviso that each property's output may be valued 
slightly differently in the marketplace. 

The grade of scheelite concentrates from the operations 
evaluated varies from 70 to 75 pet. which means output from 
all deposits fits the Metal Bulletin and International 
Tungsten Indicator definitions of standard grade concen- 
trates. However, there are differences in the chemical 
makeup of each concentrate that may make it more or less 
suited to a particular use. The actual price at which each 
- traded depends on how well the marketer of 
the concentrate is able to fulfill the needs of the customer. 
>11 as the current conditions of the market. 

Comparative prices should be interpreted carefully. Dif- 
ferences between properties of a few percent in the 
calculated average total costs have very little meaning. 
Theiv s 1( _:ee of error inherent in all cost estimates and 
some quality differences in the product of each mine. For 
either of these reasons, an estimated cost could change by 
a few percent. When comparisons to published prices are 
made, the same caution should hold. These are only reported 
prices, they have limited coverage, they are annual 
averages, and they do not include penalties or premiums 
that would be applied because of impurities or grade. 

Eleven MEC deposits that do or would produce tungsten 
as the primary product were evaluated under the assump- 
tion that scheelite 'either natural or artificial) concentrate 
is the first marketable product. Only those operations that 
already market scheelite or that can reasonably be expected 
to do so 'based on company information on marketing plans 
or chemical analysis of the ore) were classified as scheelite 
producer No U.S. properties were costed as scheelite 
produ 

Total Availability 

Approximately 553.000 t of W0 3 is potentially 

erable as scheelite (46 pet of total W0 3 available from 

evaluated dei th most of the tonnage potentially 

available from nonproducing deposits. Figure 28 shows the 



tonnages available from the nine producing deposits 
evaluated and the estimated average total cost of produc- 
tion associated with each deposit. Two curves are shown — 
the solid line represents results from the evaluations assum- 
ing a 15-pct DCFKOR. the dashed line represents the results 
at a 0-pct. or breakeven, rate. At this breakeven level of 
costs, each property is able to recover all costs of produc- 
tion, including payment of taxes and recovery of all capital 
investments, but makes no rate of return on that 
investment. 

Approximately 142.000 t of WO, in scheelite concen- 
trates is potentially available from producing deposits. At 
a 15-pct DCFROR, average total costs of production range 
from $2.30 to $6.05/lb, with the most of the tonnage 
available at under $4 lb. The weighted-average total cost 
of production for all scheelite producers is $3.33 lb of WO-,. 
The range of estimated costs is much narrower at the 0-pct 
DCFROR. with all properties having average total costs of 
production of $5 lb of W0 3 or less. At a 0-pct DCFROR the 
weighted average cost drops almost 20 pet. to $2.73 lb. and 
more than 90 pet of the tonnage is available at costs below 
the January 1983 market price of $3.63 /lb of W0 3 . 

The range of tungsten concentrate prices (in January 
1981 dollars) over the 1973 to 1983 period is given in table 
18 (see table 1 for more complete information on historical 
price trends). All of the producing properties shown in figure 
28 have experienced years when market prices were higher 
than estimated costs. Based on these evaluations, only in 
1973. 1982, and January 1983 have prices been at a level 
that would not return at least a 15-pct DCFROR for all pro- 
ducing properties. Even at the low market price existing 
in January 1983, three of the nine producers are still able 
to make at least a 15-pct DCFROR. 

By far the largest scheelite deposit evaluated is Mac- 
tung, a nonproducing prospect located on the Yukon- 
Northwest Territories border in Canada. The current 
estimate of demonstrated resources is 412.700 t of 
recoverable W0 3 , making it larger than all other scheelite 
properties combined and also the largest MEC property 



Table 18.— U.S. market price for tungsten concentrates, 
constant January 1981 dollars per pound W0 3 



1973 
1974 
1975 
1976 
1977 
1978 



Price 
$5 00 


1979 


Price 
$7 38 


7.34 


1980 


6.87 


7.09 


1981 


6.51 


8.25 


1982 


4.88 


11.42 


January 1983 


3.63 


846 


Period average 


6.99 



15-pcr DCFROR 
O-pct DCFROR 



j 



I 



I 



^.J" 



W03,l0 3 t 

Figure 28— Total W0 3 potentially available from scheelite producers at 15- 
and 0-pct DCFROR s. 



42 



evaluated. Mactung is the most expensive scheelite property 
evaluated at a 15-pct DCFROR. Still, the relatively high 
annual average prices such as existed in the mid-1970's 
would be sufficient to return a full 15 pet on required in- 
vestment at Mactung. 

Estimated costs for the' nonproducers at a 0-pct 
DCFROR are substantially lower than those from the 15-pct 
DCFROR results, reflecting the effect of the required rate 
of return on capital in the formation of a price expectation 
by a deposit owner considering development. Properties 
with the largest capital expenditures early in the life of the 
property show the largest drop in average total costs 
between a 15-pct DCFROR and a breakeven or 0-pct 
DCFROR. This point is demonstrated dramatically with 
reference to the Mactung property. Mactung, which will re- 
quire very large capital investments and several years 
development time before it can produce, shows more than 
a 63-pct decrease in estimated cost, indicating that all 
capital could be recovered, and a small profit is possible even 
at relatively low market prices. 

Annual Availability 

Current producers can supply about 12,000 t of W0 3 in 
scheelite concentrates annually when operating at full 
capacity. Figure 29 illustrates that about 80 pet of this 
amount is available from producers with average total costs 
below $4/lb of W0 3 (at a 15-pct DCFROR). Based on 
demonstrated resources only, this level of production can 
be maintained through 1988, at which time output levels 
could begin to drop fairly quickly. Barra Verde, Brazil, has 
demonstrated resources sufficient to last only through 1986, 
Kara, Australia, has resources to last through 1988, and 
Brejui, Brazil, and Cantung, Canada, run out of currently 
demonstrated resources in 1990. King Island, Australia, and 
Sangdong, Republic of Korea, two of the major producers 
at the present time, can continue to produce at current 
levels from demonstrated resources until about the year 
2000. However, the demonstrated resource figures used for 
this evaluation could substantially understate the ultimate 
production potential at many operations. 

How well scheelite producers will be able to meet poten- 
tial annual demand will be addressed in the "Tungsten 



Availability— All Product Forms Combined" (annual 
availability) section. No records are available from most 
countries of the form in which tungsten is actually consum- 
ed, and demand is generally reported as an aggregate 
amount of W0 3 (or W) consumed in all forms. The final an- 
nual availability subsection will discuss availability of all 
forms of tungsten from all sources and make comparisons 
with possible demand scenarios for all the tungsten products 
combined. 

The two nonproducers can potentially provide a substan- 
tial supplemental source of scheelite. Zangarelhas could pro- 
vide an average of over 400 t/yr of W0 3 in scheelite con 
centrates if the Boca de Lage mine and concentrator expand 
to include development of that portion of the ore body at 
the production level assumed for this evaluation. The min- 
ing plan assumed for the huge Mactung ore body models 
production at more than 3,500 t of W0 3 per year. At this 
rate Mactung could produce well beyond 2100. 

Ammonium Paratungstate (APT) 

Forty-one of the fifty-seven properties in this study were 
evaluated as APT producers. Ore from any mine can be pro- 
cessed into APT, and it is often the first standard product 
form in which it is possible to make comparisons between 
properties. 

Total Availability 

Approximately 633,000 t of W0 3 is potentially 
recoverable as APT (52 pet of total W0 3 potentially 
available from evaluated MEC deposits) from 26 producing 
and 15 nonproducing deposits, with 146,000 t (23 pet) of that 
amount available from 12 U.S. properties. Figure 30 shows 
the tonnages available as APT, at a 15-pct DCFROR, from 
all MEC deposits analyzed, as well as the amounts available 
from U.S., South American, and European deposits. 
Average total cost of production ranges from $0 to $21.00/lb 
(January 1981 dollars) of W0 3 in APT after accounting for 
byproduct credits. The weighted-average total cost of pro- 
duction for all APT properties is $12.55/lb of W0 3 . 

The range of APT prices (in January 1981 dollars) over 
the 1973 to 1983 period is given in table 19 (see table 1 for 





1 1 

$6 06 


Costs are in January 1981 dollars per 
pound of WO3 m concentrate Costs 
include a 15-pct DCFROR 


_ 


- 


$ 3 63 


^^^ - 


- 


i ' 


\ "~"~ - ~~~— — — — 


\^ 


; 1 ! 



YEAR 



Figure 29.— Annual W0 3 potentially available from scheelite producers at 
various average total costs. 



43 




— i 1 

AvJiloMf from Un.tfd Stotts 



- 



AvO'loD'e tt<yn Sc*" 


1 

r. 


- f 




WOj,l0 3 t 



Figure 30.— W0 3 potentially available as ammonium paratungstate. 



Table 19— U.S. market price for APT, constant January 
1981 dollars per pound of W0 3 



1973 
1974 
1975 
1976 
1977 
1978 



Price 
S6 80 
923 
896 
10 18 
13.48 
1041 



1979 

1980 

1981 

1982 

January 1983 

Period average 



Price 
S9.27 
8.74 
8.37 
6.66 
5.37 
8.86 



a more complete presentation of historical price trends). 

rOUfrom 11 current produ< potentially 

able at costs ranging up to $5.37 lb of WO,, which was 

the constant 'January 1981) dollar market price for API 

Jting in January 1983. Nine percent of that amount is 

mailable from two operations in the United 

Sta' 

proximately 109.000 t of V. ,lly 

available at costs ranging up to $7.00 lb ( 16,000 t, or nearly 
15 pet from the United States); 174.000 i at costs ranging 
up to $8.90 per pound, the average annual price over the 
to 1983 period < 64 .000 t. or 37 pet from the United 
States); and 319.000 t at aging up to $13.50 lb 

2 pet from the United States I, which was near 
the peak annual average price over the last decade ($13 48 
in l c '~~ 

The cui -,uth America 'fig. 30) illustrates that 

nearly 30.000 t o: coverable 

from nine mines and di inging fi 

'35 1b of WO This relatively small demonstrated 
he common practice of some companies 
and many lesser developed count),*- of only defining 
reserves at a level sufficient to plan production for the next 
' iny of these mines have been v 
or more, and the potential exi-' 
than the demonstrated level us. 

The Bolivian deposits ha 
ducers even though the first produ 
scheelite or wolframite cor 
tain impurities and are likely \|'[ 



before they reach consumers. Bolivian tax laws penalize the 
export of processed minerals more heavily than the export 
of concentrates, and concentrates are generally sold to in- 
termediaries who transport them elsewhere to be further 
processed. The evaluations done for Bolivian deposits in- 
clude transportation costs to an APT plant and the cost of 
converting the concentrates to APT. Additional costs for 
handling and marketing by intermediaries have not been 
included and could add 5 to 15 pet to the average cost 
estimated in this evaluation. 

Also shown in figure 30 is total availability of APT from 
ight European properties. Nearly 32,000 t of W0 3 in APT 
is potentially available at average total costs of production 
below the January 1983 market price of $5.37/lb of W0 3 , 
and almost 60,000 t is available at costs at or below the 
average market price ($8.86/lb) prevailing over the last 
decade. The large tonnages available from European 
deposits at cost levels above this value are mostly from non- 
producers. The Hemerdon deposit in the United Kingdom 
is the largest evaluated deposit in Europe (in terms of 
recoverable WO,), but based on current mining and mill- 
ing technology and the best available information on the 
geology, it would apparently be a relatively high-cost 
operation. 

The graphs in figure 31 illustrate total availability of 
W0 3 in APT from producing properties at both a 15-pct 
DCFROR (solid line) and a 0-pct DCFROR (dashed line). 
Approximately 35 pet (219,000 t) of the W0 3 potentially 
available in APT comes from the 26 producing tungsten 
mines. The average total cost of production for these prop- 
erties at a 15-pct DCFROR ranges from $0 to $12.65/lb of 
W0 3 . The weighted-average total cost for all producing APT 
properties is $7.10/lb of W0 3 . Eleven of the properties, with 
ible W0 3 of 52,000 t (24 pet of the total 
available from producers), have average total costs of pro- 
duction below the January 1983 market price (in terms of 
January 1981 dollars)of$5 37 II- <»IWO, Another 10 prop- 
with an additional 110,000 t of WO., have average 
total costs below thi e market price prevailing over 

ade ($8.86/lb). All of the producers have 
estimated average total costs below the peak annual 



44 



— ■ ! 1 1 

KEY 

15-pct DCFROR 

O-pct DCFROR 




T ' 1 


1 


! 


r 


- 


- 








r 






J - 




- 




1 




i 






r-S~ 


- . 




i ^ r 


.y 












) _j ' J 














- [V"~"~ 


1 1 




1 1 


1 


i 







100 125 

W0 3 , I0 3 t 



Figure 31. — Total W0 3 potentially available from ammonium 
paratungstate producers at 15- and O-pct DCFROR's. 



average price over that same period, which was over $13/lb 
in 1977. 

Seven of the eleven deposits with average total costs of 
production under $5.37/lb of W0 3 also recover one or more 
byproducts. An example of the importance of byproduct 
credits is seen in the results for Mawchi, Burma, which has 
calculated costs of production at $0/lb of W0 3 . A nearly 
equal amount of tin is recovered at Mawchi along with the 
tungsten. Tin revenues, calculated using a price of $5.53/lb 
of tin, compensate for the total cost of the operation and, 
consequently, the solved-for value of average total costs for 
Mawchi is equal to zero. 

When the producing properties are evaluated at a O-pct 
DCFROR, costs are 10 to 15 pet lower, on average, ranging 
from $0 at Mawchi, Burma (which benefits from large tin 
byproduct revenues), to $11.55/lb of W0 3 . The weighted- 
average cost for APT producers decreases to $6.10/lb W0 3 
at a O-pct DCFROR. Nearly 46 pet (101,000 t) of the total 
is available at costs below the January 1983 market price 
level ($5.37/lb). Most of the tonnage (213,000 t, or 97 pet 
of the total) is potentially available at costs below $8.86, 
the average price (January 1981 dollars) prevailing over the 
last decade. 

Figure 32 shows potential availability of W0 3 in APT 
from the 15 nonproducing deposits. The solid line illustrates 
the results from the 15-pct DCFROR evaluation and the 
dashed line illustrates the O-pct DCFROR results. More 
than 65 pet of tungsten resources potentially available as 
APT (414,000 t) come from the nonproducers. Costs range 
from $6.30 to $21.00/lb at a 15-pct DCFROR, with the 



HO 14 



> o 

< ? 



KEY 

■ 15-pct DCFROR 
O-pct DCFROR 



S 



O 50 IOO 150 200 250 300 350 400 450 

W0 3 , 103 t 

Figure 32.— Total W0 3 potentially available from ammonium 
paratungstate nonproducers at 15- and O-pct DCFROR's. 



weighted-average cost equal to $15.45/lb of W0 3 . None of 
the nonproducers can recover all costs of production (in- 
cluding the 15-pct DCFROR) at the January 1983 market 
price. However, at the average market price prevailing over 
the last decade ($8.86/lb of W0 3 ), two properties appear able 
to recover all costs. At the peak annual average price that 
prevailed in 1977, 10 properties with 100,000 t of 
recoverable W0 3 could recover all costs of production, in- 
cluding the 15-pct DCFROR. 

Estimated costs decrease more than 55 pet, on average, 
when the nonproducing properties are evaluated with no 
rate of return required on invested capital. The weighted 
average total cost for nonproducers is $6.55/lb at a O-pct 
DCFROR. At pet, about 25,000 t of W0 3 in APT is poten- 
tially available from three nonproducers at costs below the 
January 1983 market price ($5.37/lb). Almost 400,000 t of 
W0 3 (96 pet of the total available from nonproducers) is 
potentially available at costs below the average market 
price prevailing over the last decade. At a 0-pct DCFROR, 
all of the nonproducing APT properties have estimated 
average total costs of production below the peak prices of 
1977 and 1978. That is, all the nonproducers could make 
a positive rate of return on investment if market prices 
prevailed over the long run at levels equal to or greater than 
the average annual prices in 1977 or 1978. 

There are several very large deposits among the non- 
producers, with the Logtung deposit in Canada being the 
largest. Some potential cost savings measures, such as high 
grading early in the life of these large deposits, have been 
suggested in the mining literature but were not considered 
in the costing. Since all of the nonproducers were costed 
using estimated development schedules and current min- 
ing and milling methods, these average total cost estimates 
should be viewed with caution. The cost numbers are good 
estimates of the potential profitability of the deposits given 
current technology and our present understanding of the 
physical characteristics of the respective ore bodies. 
However, improved processing methods could improve the 
economic outlook for any of the deposits by the time they 
are actually developed. 

Annual Availability 

Potential annual availability of W0 3 in APT from pro- 
ducing mines is shown in figure 33. Each line on the graph 
reflects annual availability at or below different maximum 
average total cost of production (including a 15-pct 
DCFROR). About a third (5,000 t annually) of the tonnage 
potentially available in the next 3 to 5 yr from current pro- 
ducers is at average total costs (including a 15-pct DCFROR) 
under $5.37/lb, approximately the January 1981 dollar 
market price existing in January 1983. Most of the tonnage 
(14,000 1 annually) is available at less than the average an- 
nual price over the last decade ($8.86/lb of W0 3 ). In total, 
there is nearly 16,000 t/yr of W0 3 in APT potentially 
available through the decade of the 1980's at costs rang- 
ing up to $12.66/lb of W0 3 . 

After 1986, annual production from demonstrated 
resources could begin to decline rather quickly and by 1995 
projected production from current producers is less than half 
what it was at the peak. There are two reasons why the 
decline may be less than shown in these curves. First, the 
current weak market for tungsten means some operations 
will be producing at less than full capacity over the next 
few years. Second, some of the deposits, notably the Boli- 
vian deposits, are likely to have resources in excess of the 
current demonstrated level. 



45 





5 


Costs ore in Januoty 1981 dollars per 
pound of WO3 in APT Costs include 








'6 




a 15- pet DCFROR 




14 


-^S8 86-, 






12 




- 


. ^-—-^$700 






O 








§ s 








6 


$5 37 






•i 


^ 






2 




1 1 1 1 





986 S87 988 1989 1990 1991 1992 1993 1994 1995 

YEAR 

Figure 33.— Annual W0 3 potentially available from ammonium paratungstate 
producers at various average total costs. 



The amount of tungsten potentially available annually 
from deposits not yet producing is shown in figure 34. The 
pattern of annual availability reflects the set of assump- 
tions that went into the evaluation concerning the speed 
with which different deposits could develop. Each property 
was developed with the minimum necessary engineering 
and construction time allowed for, and no provision was 
made for gathering required permits, arranging financing, 
etc. A near maximum level of production from deposits not 
yet developed is forthcoming about 4 to 6 yr after the deci- 
sion to begin development. The pattern is similar at all cost 
levels displayed. 

Less than 1.000 t of annual capacity is available from 
nonproducers at costs below the constant dollar average an- 
nual price of the last decade ($8.86flb of W0 3 ). About 3,500 



t of annual capacity is potentially available at costs at or 
below the peak annual average price of 1977 ($13.48/lb of 
W0 3 ). The bulk of potential annual production from non- 
producing APT operations would require prices higher than 
have been experienced in the past in order to recover all 
costs of production, including a 15-pct DCFROR. 

Ferrotungsten 

Five properties were evaluated in this study under the 
assumption that ferrotungsten is the first marketable prod- 
uct. All these properties have ferberite as the main ore 
mineral. Three of the properties are current producers of 
ferrotungsten, and the other two are past producers of ferro- 
tungsten. Khao Soon, Thailand, was shut down in 1975 






- dollars per 
pound 0+ W0 3 in APT Costs include 
15-pcT DCFROR 




1 T"- - 




N Yew preproduction developrrent begins 






S2 .^-^~~^~^ 






/ il348_— 






/ / 




- 


^y /^ 




. 


1 ' 



-. .- 



N+IS 



Figure 34.— Annual W0 3 potentially available from ammonium paratungstate nonproducers at 
various average total costs 



46 



(after several years of production) due to chaotic political 
conditions. Nyamalilo, Uganda, has had intermittent pro- 
duction for more than 20 yr, always at a low level, but has 
not operated for the past several years. 

Total Availability 

Figure 35 illustrates total availability of ferrotungsten 
at different levels of average total costs of production. Two 
curves are shown in the figure. The solid line illustrates 
the results from the evaluation assuming a 15-pct DCFROR, 
while the dashed line illustrates the results with a 0-pct 
DCFROR. Approximately 16,400 t of W is potentially 
recoverable as ferrotungsten (2 pet of total MEC tungsten 
available). Estimated average total costs at a 15-pct 
DCFROR range between $4.35 and $15.30/lb of W, with the 
weighted-average total cost for all ferrotungsten properties 
equal to $7.40/lb of W. The three current producers (with 
a weighted-average total cost of $8.30/lb of W) account for 
over 25 pet (4,200 t) of the total tonnage. A separate graph 
for ferrotungsten producers is not provided because of the 
small number of operations. Most of the total (11,000 t) is 
potentially available from Khao Soon, Thailand, currently 
shut down because of political conditions. 

The market price used as a reference price in this sec- 
tion is in terms of its W content only (W content = 0.793 
x W0 3 content). The formula for the computed price was 
given in the "Tungsten Pricing" section of this report, and 
is based on the market price for concentrate plus a conver- 
sion charge. Table 20 gives the computed average annual 
ferrotungsten prices in January 1981 dollars from 1973 to 
January 1983, including the average price over the entire 
period. 

It should be remembered that every mine's output has 
a unique chemical makeup that will make its selling price 
unique, and comparisons of average total costs to historical 
sales prices are made for reference purposes only. 

At a 15-pct DCFROR, only one property has average 
total costs below the 1983 market price. However, four of 
the five properties have average total costs below the 
average price (January 1981 dollars) of $9.98/lb of W that 
has prevailed over the last decade. 

At a 0-pct DCFROR, costs range between $3.20 and 
$14.55/lb, with the weighted-average total costs of produc- 
tion at pet equal to $4.60/lb of W. This 38 pet cost dif- 
ference from the 15-pct results emphasizes the importance 
of capital investments in total costs for these current pro- 
ducers and past producers. Those properties with relatively 
large investments or a long development time show the 



Table 20.— U.S. market price for ferrotungsten, constant 
January 1981 dollars per pound of tungsten 



< 2> 



1 1 1 1 

KEY 


— i 1 1 


i 


- 15-pct DCFROR 




- 


0-pct DCFROR 






- 




- 


- 




- 


- 












i 










- 




i i i i i . _i 1 



Price 

1973 $7.40 

1974 10.45 

1975 10.12 

1976 11.63 

1977 15.75 

1978 11.93 



Price 

1979 $10.52 

1980 9.84 

1981 9.37 

1982 7.24 

January 1983 5.61 

Period average 9.98 



W,l0 3 t 

Figure 35. — Total W potentially available from ferrotungsten 
deposits at 15- and 0-pct DCFROR's. 



greatest reduction in development costs when evaluated at 
pet. Where mine and mill operating costs are high, and 
little capital investment is needed, the estimated average 
total cost of production drops very little when the required 
rate of return is reduced from 15 to pet. 

Annual Availability 

Approximately 400 1 of W is available in ferrotungsten 
annually from current producers operating at capacity. 
However, all the present producers except Doi Ngoem will 
have exhausted their demonstrated resources by 1990. 
Nyamalilo could develop quickly (2 to 3 yr) and would add 
up to 170 t annually of W in ferrotungsten. Khao Soon could 
take much longer to develop for two reasons: the physical 
deterioration of the mine and the facilities since its closure 
in 1978, and the troubled political climate inhibiting invest- 
ment. If Khao Soon does develop it could add nearly 700 
t/yr of W to the market, and there are sufficient 
demonstrated resources to continue production at that rate: 
for about 20 yr. 

No information is available regarding the potential for 
additional resources at Borralha (Portugal) and Cham- 
billaya (Bolivia), but it is possible that both properties could 
have several years' additional production beyond the< 
demonstrated resource level evaluated. Borralha is a small 
operation that expends little effort to define resources 
beyond the next few years' requirements. The exploration 
philosophy at Chambillaya, as with most of the Bolivian 
operations, is to develop only enough information to sup- 
port the next few years' production. 



TUNGSTEN AVAILABILITY— ALL PRODUCT 
FORMS COMBINED 

Tungsten availability has been discussed in the three 
previous sections in terms of scheelite concentrate, APT, 
or ferrotungsten. This section brings together all product 
forms and discusses the availability of tungsten as a single 
commodity. It also includes a brief discussion of the avail- 
ability of tungsten from alternative sources, such as CPEC 
deposits, stockpiles, scrap, and as byproduct tungsten from 
other mines. The section concludes by relating annual 
availability to annual consumption, based on estimated 
trend projections of demand. 

Total Availability 

MEC primary tungsten deposits evaluated in this study 
have demonstrated resources of approximately 1.2 million 
t of recoverable W0 3 . Of this total, 46 pet (553,000 1) is poten- 
tially available as scheelite concentrates, 53 pet (63,000 t) 
as APT, and 1 pet (16,400 t W or 20,680 t W0 3 equivalent) 
is potentially available as ferrotungsten. At current rates 
of production (the 1980 to 1982 average MEC production 
was nearly 29,800 t/yr of W0 3 ) these demonstrated resources 



would last about 40 yr. However, with much of the tonnage 
contained in a small number of large deposits, this may be 
a misleading indicator of the ability of the MEC's to pro- 
vide tungsten on an annual basis. The annual availability 
discussion in this section will examine remaining resources 
and annual capacities on a mine-by-mine basis. 

China and the U.S.SJR. combined have total estimated 
in situ demonstrated resources of nearly 2.2 million t of 
\V0 3 . Assum. j rati' and continuation of 

the average 19S0-S2 rate of production (17.225 t yr for 

^hinahas64yrofpro- 
n. the U.S.S.R. can produce for a 9 yr from 

deposits evaluated. Discussion of capacity-resource infor- 
mation on a mine-by-mine basis for CPEC deposits is in- 
cluded in the "Geology and Resources" section. Lesser 
amounts of tungsten are available from the rest of the 
CPEC's. The Bureau regularly reports production from 
Czechoslovakia and North Korea, for instance, but very lit- 
tle of this tungsten reaches western markets. The Bureau 
imates a reserve base for other CPEC's of 250 million 
lb of W (equivalent to 143.000 t of W0 3 >. 

The U.S. Government's stockpile contains more than 
1 yr ofMEC consumption at recent levels, but most of this 
inventory is needed to meet the stockpile goal. The excess 
tungsten in the stockpile is generally offgrade, although 
stockpile sales of tungsten could still impact the market in 
the future. Producer and consumer stockpiles also exist, but 
very little data are available concerning them. Privately 
held U.S. stocks are reported annually in the Bureau's 
Minerals Yearbook and have generally been between 20 and 
40 pet of U.S. annual consumption levels. 

Recycling has been a fairly constant source of tungsten 
in the past, generally accounting for slightly less than 15 
pet of consumption. The opportunities for recycling have 
been expanded as tungsten carbide tools have become a 
larger share of the market, and scrap could increase in im- 
portance somewhat as a component of supply in the future. 

Byproduct tungsten is also an important component of 
supply, but is very difficult to measure or to forecast. The 
United States, for example, has two large potential 
byproduct sources— the Climax molybdenum mine in Col- 
orado and the Searles Lake brine deposit in California. The 
Climax Mine contains more than 100,000 t of W0 3 . It has 
been the largest domestic tungsten source in past years 
when the mine was operating at full capacity, producing 
about 1.000 tyr of W0 3 in concentrates. However, the mine 
is currently closed owing to the weak market for 
molybdenum. A resumption of tungsten shipments from 
Climax will await the recovery of the molybdenum market, 
and has almost no relation to the state of the tungsten 
market. 

The Searles Lake deposit has about 77,000 1 of contained 
WO, in brines. A process for recovering the tungsten has 
been developed, but substantial investments would be re- 
quired before recovery is possible. As with any untried 
technology, tungsten recovery at Searles Lake remains an 
unknown until such time as the investments are made and 
the process is operational. The amount of tungsten 
recovered annually will depend on conditions in the soda 
ash market, and not on the tungsten market. 

The source and amount of byproduct tungsten from out- 
side the Unit* - rficult to estimate. Country pro- 
duction data do not generally distinguish between primary 
and byproduct tu- ran lead-zinc- 
silver operatr mall amounts of tungsten. The 
Naica mine is perhaps the largest Mexican tungsten 



byproduct source, recovering about 245 t of W0 3 in 1981. 
Many tin deposits in southeast Asian countries such as 
Burma. Malaysia, and Thailand contain small amounts of 
recoverable tungsten. The Nok Hoog tin mine in Malaysia, 
for example, produces nearly 150 t of W0 3 per year. 
Molybdenum deposits in the Republic of Korea contain 
tungsten in recoverable amounts, but the total amount of 
byproduct tungsten is insignificant in comparison to the 
Sangdong operation. 

The total amount of byproduct tungsten entering the 
! tedly impo^ant but currently is recovered 
from a large number of sources, and is difficult to account 
for. The amount of byproduct tungsten entering the market 
is a function of conditions in the markets for other primary 
products. The costs of producing byproduct tungsten do not 
appear to be a major factor at operations that are known 
to currently be recovering byproduct tungsten, but with the 
possibility of rising prices in the future, more operations 
could choose to recover the tungsten available as a 
byproduct. Little data are available with which to make 
projections as to the likely future importance of byproduct 
tungsten. 

The principal source of tungsten production in the world 
is likely to be the nearly 100 mines and deposits that do 
or would produce tungsten as the primary product. Nearly 
half of primary tungsten production currently originates 
from MEC's. Both MEC and CPEC sources could potentially 
produce more than they do now, although increases in price 
might be required to compensate for the increased costs of 
production if new MEC deposits have to be brought into pro- 
duction. Among CPEC sources, China is the most likely to 
expand production, either from existing mines or the 
development of new mines. This would reduce the upward 
pressure on price and delay the development of new MEC 
properties. 

Annual Availability 

Over 30 pet (373,000 t of W0 3 ) of total tungsten poten- 
tially available from evaluated MEC deposits is available 
from current producers. At current rates of production, pro- 
ducing deposits have an average of 14 yr of production left. 
Demonstrated resources remaining at different producing 
deposits in different countries show anywhere from 4-yr 
potential production (at some of the Bolivian deposits) to 
almost 40-yr production (at Barruecopardo, Spain). While 
it is possible that further exploration will define additional 
resources at some producing deposits (e.g., see the "Geology 
and Resources" section of this report for a discussion of the 
potential for additional resources at Bolivian deposits), it 
appears likely that one or more nonproducing deposits could 
be developed within the next 10 yr. 

The following analysis compares annual availability 
from current producers to projected annual demand in order 
to estimate the adequacy of MEC production capacity in 
meeting MEC demand. Because country production 
statistics do not generally distinguish between tungsten 
derived from primary sources and tungsten made available 
from other sources, the assumption was made for this 
analysis that the primary tungsten operations evaluated 
in this study will supply 90 pet of projected MEC demand 
'for as long as demonstrated resources last). This assumed 
production level is attainable, since combined capacity at 
all evaluated producing primary tungsten deposits in MEC's 
is equal to greater than 90 pet of the peak production level 
of 1980 (figs. 2-3). Byproduct and otherwise unaccounted for 



48 



tungsten production capacity (e.g., tungsten smuggled out 
of Malaysia and Thailand or production from small mines 
not evaluated) would make up the remainder of potential 
annual supply. 

Two alternative growth rates were used to project de- 
mand between 1983 and 1995: 3.5 and 2.0 pet per year. The 
3.5-pct growth rate was suggested in the tungsten chapter 
of the 1980 Mineral Facts and Problems (8). The 2.0-pct rate 
is included as a sensitivity analysis in light of the poor per- 
formance of the world's economies in recent years. Only 
present operating capacities and known planned expansions 
that were part of the proper* y evaluations are assumed to 
be available to fill that demand, and new mines will be 
developed as needed to keep MEC supply and demand in 
balance. All current producers were assumed to continue 
producing at capacity until all demonstrated resources are 
exhausted. 

The major element excluded from this scenario is China. 
With the world's largest known resources (China can con- 
tinue to produce at current rates from known resources for 
more than 60 yr), China could expand production and limit 
the number of new operations required, or reduce tungsten 
shipments and put upward pressure on price. The assump- 
tion was made that the current situation, with MEC supply 
approximately equal to MEC demand, will continue to hold 
in the future as it has for the last 10 yr (see figure 3). 

Figure 36 shows annual availability from all current 
MEC producers combined, without reference to price. The 
straight lines show simple trend projections of potential de- 
mand for tungsten in MEC's, calculated as either a 3.5- or 
a 2.0-pct growth rate after 1984. All demand projections 
shown are for 90 pet of the total MEC demand to facilitate 
comparison with the annual availability curve. Since 
preliminary data for 1983 indicate MEC consumption is ab- 
normally low (as was 1982— see table 3), several assump- 
tions were made concerning what would be "normal" de- 
mand in future years. For this analysis, 1983 consumption 
is assumed equal to 1982's, and 1984 consumption is as- 
sumed to return to the level of 1981. Consumption levels 



for 1985 and beyond are calculated as a fixed percentage 
growth per year from the 1984 base. 

As seen in figure 36, current producers can supply more 
than the amount required for the next 4 to 5 yr. If excess 
production capacity in the 1983-86 period leads to reduced 
levels of production, then the producing lives at some cur- 
rent operations will be extended and will offset apparent 
production shortfalls in the 1987-88 period. By 1989 or 1990, 
however, several of the nonproducers may need to be 
developed. There are five nonproducers whose estimated 
average total costs of production are lower than the average 
market prices prevailing over the past decade. They could 
begin production by 1990 to correspond with projected in- 
creases in demand. If developed, they will add about 2,400 
t of W0 3 annual capacity. 

After 1990 there could be a rapid dropoff in availabil- 
ity from current producers. The Cantung deposit in Canada, 
for instance, will be depleted of currently reported 
demonstrated resources by 1991. Also depleted by 1990 are 
all but three of the Bolivian deposits (a drop of 2,300 t 
annual capacity) and two of three Brazilian deposits (1,000 
t annual capacity). Mawchi, Pasto Bueno, Kara, Borralha, 
and Strawberry could also have exhausted their currently 
demonstrated resources by 1990. It has been emphasized 
in previous sections of this report that many of the current 
producers might have resources larger than the 
demonstrated level used in the evaluations, but this is 
uncertain and new property development could be required 
by about 1990. 

AMAX has performed preliminary engineering and 
evaluation studies on the Mactung (Canada) property, which 
is estimated to be the lowest cost of the large nonproduc- 
ing properties evaluated. Mactung would add more than 
3,500 t of W0 3 annually if it is developed at the capacity 
assumed for the evaluation. The estimated average total 
cost of production at Mactung is higher than the average 
annual price for scheelite has been over the last decade, but 
still below the peak annual average prices of 1977-78. 

Throughout the 1990's total availability from current 



40 

38 - 

36 

34 

32 

30 

28 

26 

24 

22 

20 







1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 

YEAR 

Figure 36.— Annual MEC W0 3 availability and projected demand, 1983-95. 



49 



producers could continue as currently demonstrated 
urces are depleted. According to the evaluation results. 
Panasquiera (Portugal) has demonstrated resources to last 
only through 1994. Mittersill Austria", is depleted of 
demonstrated resources in 1H94. and Yxsjoberg (Sweden), 
eported demonstrated resources to last only through 
1995 i assuming full capacity levels of production". If addi- 
tional res - ire not found at some of those currently 
producing deposits, then more of the nonproducers may 
have to be developed. 

The Pilot Mountain. Thompson Creek, Indian Springs, 
and Queen properties in the L'nited States all 

nated average total costs below past peak prices. 
Their combined annual capacity would be nearly 2.600 t 
of WO* Other properties with estimated average total costs 
below past peak prices are located in Mexico. Namibia, 
Thailand, aid Uganda. Combined annual capacities from 
all nonproducers with average total costs of production 
below past peak prices is about 9.400 t of W0 3 . 

If current produ not extend their reserves (and 

therefore their producing lives) beyond the demonstrated 
resource level used in these evaluations, then by the 
mid-1990s some of the more costly deposits may have to 
be developed. Nearly 7.600 t of annual W0 3 production 
capacity would be available from six nonproducers (all 
evaluated as APT properties" with estimated average total 
rid $21.00 lb of W0 3 . For any of these 
properties to develop, there will have to be an expectation 
of higher prices than have prevailed in the past. 

There are many factors that could allow a longer-term 
supply-demand balance than is indicated by the availabil- 
-dy results. Principal among these is the possibility 
of expanding the resource base at some of the properties. 
For many of the deposits, lower grade resources or satellite 
ore bodies are known to exist, but have not been defined 
at the demonstrated level. A second possibility is that new 
producers could develop at annual capacities larger than 
those used in the evaluations. Mactung certainly has 
enough resources to support a capacity larger than assum- 



ed for evaluation purposes, but the capacity AMAX chooses 
to develop the property at will partially depend on the 
market situation existing at that time. 

Also of major importance to the future supply-demand 
balance is the possibility of expansion or contraction of 
Chinese exports to the MEC's. An expansion of exports 
could delay the development of new producers for many 
years (or even cause some of the higher cost current pro- 
ducers to shut down), while a contraction of exports would 
put immediate upward pressure on price and spur 
development. 

In the absence of major expansions of tungsten produc- 
tion and exports by the Chinese, it appears clear that an 
emphasis on exploration is warranted. Whether that ex- 
ploration focuses on extending currently known ore bodies 
or attempts to locate new ore bodies, this investigation sup- 
ports the idea that low-cost ore bodies can probably be 
developed in the 1990's to replace other properties whose 
resources are being depleted. 

If prices do rise because of higher costs at newly 
developed operations, this would be an incentive for more 
scrap recycling. Another possible response to higher market 
prices (if they occur) is expanded byproduct tungsten sup- 
plies, but there are little data available concerning the 
amount of tungsten not presently recovered. 

Lastly, there is the possibility that there will be ad- 
justments in potential demand. If higher prices or availabil- 
ity become a problem, some substitutions away from 
tungsten could be made, reducing the need for new proper- 
ty development. It is also possible that demand growth could 
be much lower than the rates assumed for this analysis. 
If there is no growth in demand from 1982-83 levels, cur- 
rent producers could supply the market until nearly 1995 
from currently demonstrated resources. In fact, some of the 
current producers appear to be operating at a loss with cur- 
rent market prices (based on the results of the evaluations) 
and might be forced to close temporarily if there is no 
growth in tungsten demand. 



CONCLUSIONS 



At the demonstrated resource level, the 57 deposits and 
properties in 19 MEC's contain an estimated 1.2 million 
t of recoverable WO„ of which more than 30 pet (373,000 
from producing mines or temporarily shut down opera- 
The remainder is from deposits that have either never 
produced or would require large capital investments to once 
again become producing properties. Canada has the largest 
recoverable demonstrated resources among the MEC's, with 
53 pet of the total. The United States and Australia account 
for 12 and 9 pet, respe. total recoverable WO, 

in MEC deposits evaluated. 

nstrated recoverable resources in 
MK ' 'entially available as WO, 

in Al ie total amount available as APT. 35 pet 

'219 romproducir pet of the 

total amount of recoverable V\ I nlable as 

APT is contained in the largi i d Logtung deposit 

in Canada. 

More than 7 pet of the total WO ,1,1.- from all 

uated a^ APT - potentially 

available at or below an average total lb of 



WO„ which was the January 1983 market price of APT. 
The weighted-average total cost for APT producers is 
$7.10/lb, and the weighted-average total cost for all proper- 
ties evaluated as APT operations is $12.55/lb. 

Approximately 553,000 t of recoverable W0 3 is poten- 
tially available as high-grade natural or artificial scheelite, 
26 pet (142,000 t) from producers. Seventy-two percent is 
contained in the (nonproducing) Mactung, Canada, deposit. 

Sixteen percent of the total recoverable W0 3 in all 
deposits evaluated as scheelite operations is potentially 
available at or below an average total cost of $3.63/lb of 
WO„ which was the January 1983 market price for 
tungsten concentrate. Nearly two-thirds of the W0 3 
recoverable at or below that cost is from the Sangdong 
operation in the Republic of Korea. The weighted-average 
total cost for scheelite producers is $3.33/lb of W0 3 , and for 
all scheelite properties combined it is $7.05/lb. 

About 16,400 t of recoverable W (20,700 t equivalent 
W0 8 ) i pot* otially available as ferrotungsten, 26 pet from 
producers Seventy seven percent of the total W recoverable 
as ferrotungsten is from deposits in Thailand. 



50 



At an average total cost of $5.61 lb of W in ferrotungsten 
uhe January 1983 market price in terms of January 1981 
dollars». only one property. Doi Ngoem in Thailand, can 
realize a 15-pct rate of return. This deposit accounts for 10 
pet of the total amount of \V available from all deposits 
evaluated as ferrotungsten properties. The weighted- 
average total cost for all ferrotungsten producers is $8.30 lb 
ofW. 

A U S. deposits were evaluated with APT as the 
primary final product. There is approximate v 146.000 t (23 
pet of the total tonnage from all deposits e\ aluated as APT 
producers" of recoverable WO, potentially available from 
- deposits. Less than 3 pet of recoverable \V0 3 in APT 
from U.S. deposits is potentially available at an average 
total cost of $5.37 lb of \VO : , or less uhe January 1983 
market price 1 : an additional 8 pet of the total is available 
at costs up to $7.00 lb. The weighted-average total cost of 
APT producers in the United States is $7.75 lb. and for all 
S properties evaluated the weighted-average total cost 

-'.301b. 

The United States is likely to continue to rely on im- 
ports for a substantial portion of its tungsten consumption. 
If all evaluated U.S. properties were to produce at assumed 
full capacity levels, total annual production would be only 



6,000 to 7.000 t of recoverable WO„ which is equivalent 
to approximately 60 to 70 pet of estimated reported average 
U.S. consumption over the 1980 to 1982 period. 

This analysis indicates that the amount of tungsten 
potentially available from producing MEC deposits 
evaluated could be substantially less than consumption by 
the early 1990's owing to depletion of currently 
demonstrated resources. If additional demonstrated 
resources are not defined at producing operations, then the 
consumption-production gap will need to be filled either by 
development of evaluated nonproducers, development of cur- 
rently unknown deposits, or increased exports from China. 

Owing to its large tungsten resource (40 pet of the total 
recoverable W0 3 in all deposits examined), China has the 
potential to become an increasingly important factor in the 
world tungsten supply-demand picture. At estimated 1982 
production levels, China has sufficient demonstrated 
resources to last for more than 60 yr. The U.S.S.R., with 
an estimated 433,000 t of recoverable W0 3 ( 16 pet of the 
total in all deposits examined), will likely continue to be 
a net tungsten importer and could have an important future 
effect on the demand side of the world supply-demand 
relationship. 



51 



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13. Staff, Pacific Copper Limited (Sydney, Australia). Torrington 
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14. Primary Tungsten Association (London). Bull. 6, Feb. 1979, 
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15. Mining Journal (London). Go-Ahead for Chicote Grande. V. 
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16. AMAX Inc. Annual Report, 1982. P. 8. 

17. Rowe, J. D. Encouraging Results From the Logjam Creek 
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18. AMAX Inc. Tungsten News. V. 21, No. 1, winter 1983, 27 pp. 

19. Atkinson, J. R., G. Kooiman, and H. J. Coates. Geology of 
Mount Pleasant Tungsten, New Brunswick. Can. Min. J., v. 102, 
Apr. 1982, pp. 73-75. 

20. Petruck, W. The Tungsten-Bismuth-Molybdenum Deposit of 
Brunswick Tin Mines Ltd.: Its Mode of Occurrence, Mineralogy and 
Amenability to Mineral Beneficiation. CIM Bull., Apr. 1973, pp. 
113-130. 

21. Beziat, P., J. P. Prouhet, and F. Tollon. The Montredon- 
Labessonie (Tarn) District. Paper in Proceedings, 26th International 
Geologic Congress (Paris, France, July 7-17, 1980). Societe Miniere 
de Montredon, 1980, pp. 1-27. 

22. Bureau of Geologic and Mineral Research (BRGM). Discus- 



sion of a tungsten deposit at Salau, France. Sept. 1980, 15 pp.; 
available upon request from T. F. Anstett, BuMines, Denver, CO. 

23. Mining Journal (London). Minas da Borralha. V. 292, No. 
7491, Mar. 16, 1979, p. 202. 

24. Mining Annual Review. 1983, 534 pp. 

25. Smith, A. Mining at Panasqueira, Portugal. Inst. Min. Metall. 
(London), July 1979, 7 pp. 

26. Farrar, E., A. H. Clark, and D. J. Kim. Age of the Sangdong 
Tungsten Deposit, Republic of Korea and Its Bearing on the 
Metallogeny of the Southern Korean Peninsula. Econ. Geol., v. 73, 
1978, pp. 547-566. 

27. Engineering and Mining Journal. International Directory 
of Mining and Mineral Processing Operations. 1981, 660 pp. 

28. Mining Magazine (London). Turn Round at Yxsjoberg. June 

1980, pp. 519-531. 

29. Goodwin, P., and S. Vimolset. Mines and Mineral Deposits 
of Thailand. Paul F. Scholia and Associates, Bangkok, Thailand, 

1981, 227 pp. 

30. Karahan, S., A. Demirci, and R. Atademir. Turkish Tungsten 
Producer Redesigns for Efficiency. World Min., v. 33, Sept. 1980, 
pp. 46-48. 

31. Reedman, A. J. Partly Remobilized Syngenetic Tungsten 
Deposit at Nyamalilo Mine. Overseas Geology and Mineral 
Resources Paper No. 41. Inst. Geol. Sciences, London, 1973, pp. 
101-106. 

32. Mining Magazine (London). Hemerdon— Britain's Largest 
Tungsten Deposit. Oct. 1979, pp. 342-351. 

33. Engineering and Mining Journal. Firms Developing a Large 
Tungsten Deposit in Elko County, Nevada. V. 171, Dec. 1970, p. 96. 

34. Mining Journal (London). Titanium, Molybdenum and 
Tungsten. V. 294, No. 7545, Mar. 28, 1980, p. 250. 

35. . Mining Annual Review. 1982, 568 pp. 

36. Mining Annual Review. 1981, 632 pp. 

37. _ _ . Mining Annual Review. 1978, 615 pp. 

38. Wylle, R. J. M., and D. Pazour. Xihuashan Mines, Mills 3000 
Daily Tons Tungsten Ore. World Min., Oct. 1979, pp. 92-97. 

39. Mining Journal (London). Soviet Tungsten Molybdenum Min- 
ing. Jan. 1981, pp. 104-105. 

40. Shcheglov, A. D., and T. V. Butkevich. Deposits of Tungsten. 
Ch. in Ore Deposits of the USSR, ed. by V. I. Smirnov. Pitman 
Publishing Ltd. (London), v. Ill, 1977, 492 pp. 

41. Altringer, P. B., P. T. Brooks, and W. A. McKinney. Selec- 
tive Extraction of Tungsten From Searles Lake Brines. Sep. Sci. 
Technol., v. 16, No. 9, 1981, pp. 1053-1069. 

42. Clement, G. K, Jr., R. L. Miller, P. A. Seibert, L. Avery, and 
H. Bennett. Capital and Operating Cost Estimating System Manual 
for Mining and Beneficiation of Metallic and Nonmetallic Minerals 
Except Fossil Fuels in the United States and Canada. BuMines 
Spec. Publ., 1980, 149 pp.; also available as STRAAM Engineers, 
Inc. Capital and Operating Cost Estimating Sys* Q m Handbook- 
Mining and Beneficiation of Metallic and Non dllic Minerals 
Except Fossil Fuels in the United States an mada (contract 
J0255026), 1977, 374 pp.; available from U.F vernment Print- 
ing Office, stock No. 024-004-0215-6. 



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